New!
Get regular updates about newly solved problems
via algebra.com's RSS system.
Recent problems solved by 'solver91311'
solver91311 answered: 16856 problems
Jump to solutions: 0..29 , 30..59 , 60..89 , 90..119 , 120..149 , 150..179 , 180..209 , 210..239 , 240..269 , 270..299 , 300..329 , 330..359 , 360..389 , 390..419 , 420..449 , 450..479 , 480..509 , 510..539 , 540..569 , 570..599 , 600..629 , 630..659 , 660..689 , 690..719 , 720..749 , 750..779 , 780..809 , 810..839 , 840..869 , 870..899 , 900..929 , 930..959 , 960..989 , 990..1019 , 1020..1049 , 1050..1079 , 1080..1109 , 1110..1139 , 1140..1169 , 1170..1199 , 1200..1229 , 1230..1259 , 1260..1289 , 1290..1319 , 1320..1349 , 1350..1379 , 1380..1409 , 1410..1439 , 1440..1469 , 1470..1499 , 1500..1529 , 1530..1559 , 1560..1589 , 1590..1619 , 1620..1649 , 1650..1679 , 1680..1709 , 1710..1739 , 1740..1769 , 1770..1799 , 1800..1829 , 1830..1859 , 1860..1889 , 1890..1919 , 1920..1949 , 1950..1979 , 1980..2009 , 2010..2039 , 2040..2069 , 2070..2099 , 2100..2129 , 2130..2159 , 2160..2189 , 2190..2219 , 2220..2249 , 2250..2279 , 2280..2309 , 2310..2339 , 2340..2369 , 2370..2399 , 2400..2429 , 2430..2459 , 2460..2489 , 2490..2519 , 2520..2549 , 2550..2579 , 2580..2609 , 2610..2639 , 2640..2669 , 2670..2699 , 2700..2729 , 2730..2759 , 2760..2789 , 2790..2819 , 2820..2849 , 2850..2879 , 2880..2909 , 2910..2939 , 2940..2969 , 2970..2999 , 3000..3029 , 3030..3059 , 3060..3089 , 3090..3119 , 3120..3149 , 3150..3179 , 3180..3209 , 3210..3239 , 3240..3269 , 3270..3299 , 3300..3329 , 3330..3359 , 3360..3389 , 3390..3419 , 3420..3449 , 3450..3479 , 3480..3509 , 3510..3539 , 3540..3569 , 3570..3599 , 3600..3629 , 3630..3659 , 3660..3689 , 3690..3719 , 3720..3749 , 3750..3779 , 3780..3809 , 3810..3839 , 3840..3869 , 3870..3899 , 3900..3929 , 3930..3959 , 3960..3989 , 3990..4019 , 4020..4049 , 4050..4079 , 4080..4109 , 4110..4139 , 4140..4169 , 4170..4199 , 4200..4229 , 4230..4259 , 4260..4289 , 4290..4319 , 4320..4349 , 4350..4379 , 4380..4409 , 4410..4439 , 4440..4469 , 4470..4499 , 4500..4529 , 4530..4559 , 4560..4589 , 4590..4619 , 4620..4649 , 4650..4679 , 4680..4709 , 4710..4739 , 4740..4769 , 4770..4799 , 4800..4829 , 4830..4859 , 4860..4889 , 4890..4919 , 4920..4949 , 4950..4979 , 4980..5009 , 5010..5039 , 5040..5069 , 5070..5099 , 5100..5129 , 5130..5159 , 5160..5189 , 5190..5219 , 5220..5249 , 5250..5279 , 5280..5309 , 5310..5339 , 5340..5369 , 5370..5399 , 5400..5429 , 5430..5459 , 5460..5489 , 5490..5519 , 5520..5549 , 5550..5579 , 5580..5609 , 5610..5639 , 5640..5669 , 5670..5699 , 5700..5729 , 5730..5759 , 5760..5789 , 5790..5819 , 5820..5849 , 5850..5879 , 5880..5909 , 5910..5939 , 5940..5969 , 5970..5999 , 6000..6029 , 6030..6059 , 6060..6089 , 6090..6119 , 6120..6149 , 6150..6179 , 6180..6209 , 6210..6239 , 6240..6269 , 6270..6299 , 6300..6329 , 6330..6359 , 6360..6389 , 6390..6419 , 6420..6449 , 6450..6479 , 6480..6509 , 6510..6539 , 6540..6569 , 6570..6599 , 6600..6629 , 6630..6659 , 6660..6689 , 6690..6719 , 6720..6749 , 6750..6779 , 6780..6809 , 6810..6839 , 6840..6869 , 6870..6899 , 6900..6929 , 6930..6959 , 6960..6989 , 6990..7019 , 7020..7049 , 7050..7079 , 7080..7109 , 7110..7139 , 7140..7169 , 7170..7199 , 7200..7229 , 7230..7259 , 7260..7289 , 7290..7319 , 7320..7349 , 7350..7379 , 7380..7409 , 7410..7439 , 7440..7469 , 7470..7499 , 7500..7529 , 7530..7559 , 7560..7589 , 7590..7619 , 7620..7649 , 7650..7679 , 7680..7709 , 7710..7739 , 7740..7769 , 7770..7799 , 7800..7829 , 7830..7859 , 7860..7889 , 7890..7919 , 7920..7949 , 7950..7979 , 7980..8009 , 8010..8039 , 8040..8069 , 8070..8099 , 8100..8129 , 8130..8159 , 8160..8189 , 8190..8219 , 8220..8249 , 8250..8279 , 8280..8309 , 8310..8339 , 8340..8369 , 8370..8399 , 8400..8429 , 8430..8459 , 8460..8489 , 8490..8519 , 8520..8549 , 8550..8579 , 8580..8609 , 8610..8639 , 8640..8669 , 8670..8699 , 8700..8729 , 8730..8759 , 8760..8789 , 8790..8819 , 8820..8849 , 8850..8879 , 8880..8909 , 8910..8939 , 8940..8969 , 8970..8999 , 9000..9029 , 9030..9059 , 9060..9089 , 9090..9119 , 9120..9149 , 9150..9179 , 9180..9209 , 9210..9239 , 9240..9269 , 9270..9299 , 9300..9329 , 9330..9359 , 9360..9389 , 9390..9419 , 9420..9449 , 9450..9479 , 9480..9509 , 9510..9539 , 9540..9569 , 9570..9599 , 9600..9629 , 9630..9659 , 9660..9689 , 9690..9719 , 9720..9749 , 9750..9779 , 9780..9809 , 9810..9839 , 9840..9869 , 9870..9899 , 9900..9929 , 9930..9959 , 9960..9989 , 9990..10019 , 10020..10049 , 10050..10079 , 10080..10109 , 10110..10139 , 10140..10169 , 10170..10199 , 10200..10229 , 10230..10259 , 10260..10289 , 10290..10319 , 10320..10349 , 10350..10379 , 10380..10409 , 10410..10439 , 10440..10469 , 10470..10499 , 10500..10529 , 10530..10559 , 10560..10589 , 10590..10619 , 10620..10649 , 10650..10679 , 10680..10709 , 10710..10739 , 10740..10769 , 10770..10799 , 10800..10829 , 10830..10859 , 10860..10889 , 10890..10919 , 10920..10949 , 10950..10979 , 10980..11009 , 11010..11039 , 11040..11069 , 11070..11099 , 11100..11129 , 11130..11159 , 11160..11189 , 11190..11219 , 11220..11249 , 11250..11279 , 11280..11309 , 11310..11339 , 11340..11369 , 11370..11399 , 11400..11429 , 11430..11459 , 11460..11489 , 11490..11519 , 11520..11549 , 11550..11579 , 11580..11609 , 11610..11639 , 11640..11669 , 11670..11699 , 11700..11729 , 11730..11759 , 11760..11789 , 11790..11819 , 11820..11849 , 11850..11879 , 11880..11909 , 11910..11939 , 11940..11969 , 11970..11999 , 12000..12029 , 12030..12059 , 12060..12089 , 12090..12119 , 12120..12149 , 12150..12179 , 12180..12209 , 12210..12239 , 12240..12269 , 12270..12299 , 12300..12329 , 12330..12359 , 12360..12389 , 12390..12419 , 12420..12449 , 12450..12479 , 12480..12509 , 12510..12539 , 12540..12569 , 12570..12599 , 12600..12629 , 12630..12659 , 12660..12689 , 12690..12719 , 12720..12749 , 12750..12779 , 12780..12809 , 12810..12839 , 12840..12869 , 12870..12899 , 12900..12929 , 12930..12959 , 12960..12989 , 12990..13019 , 13020..13049 , 13050..13079 , 13080..13109 , 13110..13139 , 13140..13169 , 13170..13199 , 13200..13229 , 13230..13259 , 13260..13289 , 13290..13319 , 13320..13349 , 13350..13379 , 13380..13409 , 13410..13439 , 13440..13469 , 13470..13499 , 13500..13529 , 13530..13559 , 13560..13589 , 13590..13619 , 13620..13649 , 13650..13679 , 13680..13709 , 13710..13739 , 13740..13769 , 13770..13799 , 13800..13829 , 13830..13859 , 13860..13889 , 13890..13919 , 13920..13949 , 13950..13979 , 13980..14009 , 14010..14039 , 14040..14069 , 14070..14099 , 14100..14129 , 14130..14159 , 14160..14189 , 14190..14219 , 14220..14249 , 14250..14279 , 14280..14309 , 14310..14339 , 14340..14369 , 14370..14399 , 14400..14429 , 14430..14459 , 14460..14489 , 14490..14519 , 14520..14549 , 14550..14579 , 14580..14609 , 14610..14639 , 14640..14669 , 14670..14699 , 14700..14729 , 14730..14759 , 14760..14789 , 14790..14819 , 14820..14849 , 14850..14879 , 14880..14909 , 14910..14939 , 14940..14969 , 14970..14999 , 15000..15029 , 15030..15059 , 15060..15089 , 15090..15119 , 15120..15149 , 15150..15179 , 15180..15209 , 15210..15239 , 15240..15269 , 15270..15299 , 15300..15329 , 15330..15359 , 15360..15389 , 15390..15419 , 15420..15449 , 15450..15479 , 15480..15509 , 15510..15539 , 15540..15569 , 15570..15599 , 15600..15629 , 15630..15659 , 15660..15689 , 15690..15719 , 15720..15749 , 15750..15779 , 15780..15809 , 15810..15839 , 15840..15869 , 15870..15899 , 15900..15929 , 15930..15959 , 15960..15989 , 15990..16019 , 16020..16049 , 16050..16079 , 16080..16109 , 16110..16139 , 16140..16169 , 16170..16199 , 16200..16229 , 16230..16259 , 16260..16289 , 16290..16319 , 16320..16349 , 16350..16379 , 16380..16409 , 16410..16439 , 16440..16469 , 16470..16499 , 16500..16529 , 16530..16559 , 16560..16589 , 16590..16619 , 16620..16649 , 16650..16679 , 16680..16709 , 16710..16739 , 16740..16769 , 16770..16799 , 16800..16829 , 16830..16859, >>NextGraphs/409457: still not sure of this answer. graph (-2,5) slope of -1 I know the formula is y=mx+b so would that be y=-1x+5 so then -1x+5-1x+5 x= -5 or am i way off?? 1 solutions
Answer 288205 by solver91311(16868) on 2011-02-15 12:01:47 (Show Source):
You can put this solution on YOUR website!
Way off is putting it mildly.
is the slope-intercept form, where is the slope and is the -coordinate of the -intercept -- that is, the point where the graph intersects the -axis.
But here the given point is which has a non-zero -coordinate and is therefore certainly NOT a point on the -axis. Hence, is NOT the -intercept, and .
What you are trying to use is a formula that is inappropriate to the situation. Furthermore, I think that using any formula at all is inappropriate to what this question is asking you to do.
Step 1: Plot the point .
Step 2: Recognize that a slope of -1 means that whenever the value increases by some amount, the value decreases by that same amount. You can also go the other way and increase when decreasing , if such pleases you.
Step 3: Starting at the point plotted in step 1, move to the right some number of units, stop, and then move down that same number of units. (Alternatively, move to the left some number of units and then up that same number of units) Plot the new point.
Step 4: Draw a line that passes through the two plotted points. Done.
Now if you want the equation of the line you just graphed, that is another story and definately NOT what the question asked you to do. But here is the process:
Since you are given an arbitrary point that is not the -intercept and the slope, use the point-slope form of an equation of a line:
where are the coordinates of the given point and is the given slope.
John

My calculator said it, I believe it, that settles it
|
Linear-equations/409267: My question in my math book is asking this-
Passes through the point (-6,5) and is parallel to the line x-2y=8
how do I solve this? I don't understand it and need help with the steps on how to do it.. 1 solutions
Answer 288145 by solver91311(16868) on 2011-02-14 23:50:24 (Show Source):
|
Polynomials-and-rational-expressions/409158: hi, I am solving by quadraic formula -b sqrt (b2-4ac)/(2a)
x^2+2x=168
x^2+2x-168=168-168
x^2+2x-168=0
-2 +- sqrt (2^2-4(1)(-168)/(2(1))
-2 +- sqrt (4-672)/(2)
-2 +- sqrt (668)/(2) This is where I am lost. It's not a perfect square, so
what do I do now? I choose factors.
-2 +- sqrt ((4(167))/(2)
-2 +- 2 sqrt (167)/(2)
common denominator of 2
-1 sqrt(167)/(2)
Would you help me understand where I went wrong and how to do it right? 1 solutions
Answer 288088 by solver91311(16868) on 2011-02-14 20:21:34 (Show Source):
|
Word_Problems_With_Coins/409090: I need help with a word problem. This is what I have so far:
Joe has a collection of nickels and dimes that is worth $3.95. If the number of dimes was doubled and the number of nickels was increased by 21, the value of the coins would be $8.40. How many nickels and dimes does he have?
first part:
dimes value + nickles value = total amount
(value of a dime)(# of dimes) + (value of a nickle)(# of nickles) = total amount
(0.10)(# of dimes) + (0.05)(# of nickles) = 3.95
(0.10)(d) + (0.05)(n) = 3.95
so d = number of dimes we start with
n = number of nickles we start with
second part:
dimes value + nickles value = total amount
(value of a dime)(# of dimes) + (value of a nickle)(# of nickles) = total amount
(0.10)(2*d) + (0.05)(n + 21) = 8.40
because we're supposed to have double (*2 the dimes) and 21 more nickles
The two equations are then:
(0.10)(d) + (0.05)(n) = 3.95
(0.10)(2d) + (0.05)(n + 21) = 8.40 1 solutions
Answer 288085 by solver91311(16868) on 2011-02-14 20:11:00 (Show Source):
You can put this solution on YOUR website!
What you have done so far is absolutely spot on correct, but I'm going to show you a little trick that will get rid of all of the ugly decimal coefficients so that you are much less likely to make any arithmetic errors.
While it is true that a dime has a value of 0.10 dollars, it also can be said to have a value of 10 cents. Likewise a nickel is worth 5 cents. Furthermore, the total value of the coins in either situation can be said to be 395 cents or 840 cents.
Now we can write the equations as:
And
Much tidier, no?
A little manipulation gets us:
Multiply the first equation by -1:
Then add the two equations, term by term:
And that leads us to
Meaning we started with 34 dimes, and it should follow directly from that fact that we started with 11 nickels accounting for the 55 cents remaining in the $3.95.
Checking our work: If we have twice the dimes, or 68 dimes, we have $6.80 in dimes and an additional 21 nickels would be 55 cents plus $1.05 or $1.60. Finally, $6.80 plus $1.60 is indeed $8.40. Ta Da!
John

My calculator said it, I believe it, that settles it
|
Polynomials-and-rational-expressions/408282: Hi, I finished this equation and would like to know if you would check my answer. My textbook answer is says 1 but I got 1 (1)(11). I would like to know how to do the problem correctly. Thanks.
(c+5)/(7)+(c-3)/(4)=(5)/(14)
common demoninator 28 and multiply by it.
28 (c+5)/(7)+ 28(c-3)/(4)= 28(5)/(14)
4c+5+7c-3=10
11c+2=10
-2 +2
(11c)/(11c)=12/11
c=1 (1)/(11) 1 solutions
Answer 287681 by solver91311(16868) on 2011-02-12 21:31:50 (Show Source):
|
Probability-and-statistics/408081: 6. Each day a quality engineer selects a random sample of 100 bolts from the day’s production, measures their lengths, and computes a 95% confidence interval for the mean length of all the bolts manufactured that day. What is the probability that more than 15 of the confidence intervals constructed in the next 250 days will fail to cover the true mean?
7. On a certain day, a large number of fuses were manufactured, each rated at 15A. A sample of 75 fuses is drawn from the day’s production, and 17 of them were found to have burnout amperages greater than 15A.
a. Find a 95% confidence interval for the proportion of fuses manufactured that day whose burnout amperage is greater than 15A.
b. Find a 98% confidence interval for the proportion of fuses manufactured that day whose burnout amperage is greater than 15A.
c. Find the sample size needed for a 95% confidence interval to specify the proportion to within ±0.05
d. Find the sample size needed for a 98% confidence interval to specify the proportion to within ±0.05
e. If a 95% confidence interval is computed each day for 200 days, what is the probability that more than 192 of the confidence intervals cover the true proportions?
8. A random sample of 400 electronic components manufactured by a certain process are tested, and 30 are found to be defective.
a. Let p represent the proportion of components manufactured by this process that are defective. Find a 95% confidence interval for p.
b. How many components must be sampled so that the 95% confidence interval will specify the proportion defective to within ±0.02?
9. A chemist made 8 independent measurements of the melting point of tungsten. She obtained a sample mean of 3410.14oC and a sample standard deviation of 1.018oC.
a. Find a 95% confidence interval for the melting point of tungsten
b. Find a 99% confidence interval for the melting point of tungsten
c. If the eight measurements had been 3409.76, 3409.80, 3412.66, 3409.79, 3409.76, 3409.77, 3409.80, and 3409.78, would the confidence intervals found in parts (a) and (b) be valid? Explain.
1 solutions
Answer 287538 by solver91311(16868) on 2011-02-12 00:44:13 (Show Source):
|
Evaluation_Word_Problems/408079: I have two questions to ask here, the first is:
1) Pip can run four times as fast as she walks. One day she walked for 3 hours and ran for 2 hours. If she covered 55km altogether. How fast did she walk?
The second one is:
2) How many litres of 15% sugar solution must be added to 5 lires of 10$ sugar solution to make a 12% sugar solution?
Please Help! 1 solutions
Answer 287537 by solver91311(16868) on 2011-02-12 00:43:09 (Show Source):
|
Miscellaneous_Word_Problems/408057: Hi there,
My question: For this linear equation y=-(2/3) x+30 I have to graph the x and y intercepts, and determine the heigth of the laser beam when the laser is 30 feet from the building...
For this linear equation y=-(2/3) x+30
A1} the Y axis represents the height (above ground) in feet.
A2} the X axis represents the distance (from the building) measured in feet.
This problem has asked me to interpret the results graphically. I have graphed the following values:
The x intercept or the point where the value crosses the x axis represents the point where the laser beams touches the ground. The y intercept, the point where the value crosses the y axis which represents the laser starting point or point where man is located.
A3} in the equation y=-(2/3) x+30 y=mx+b format (slope intercept)
(b) Represents the height of the window
(x)Represents the point where the light intercepts the ground.
A4} I solved this question by first drawing a grid, starting at the window point (0, 30)Then I used my slope of -2/3 to determine the value of 42 feet out from the building when the lights beam intercepts the ground. (42, 0)
I have found the light to be 42feet out (x value), 30feet high(y value) by using (rise over run) or slope of -2/3.
A5} Quadrant 2 is the only relevant quadrant for this problem. If we were doing a standard graphed linear equation, we would include quad. 1, 2 and 3 but since we are not including the area under the ground quad 3 is excluded, and since the beam is directional, quad 1 is also excluded. Quad four is also excluded because in either scenario, the plotted points are never on that plane/ quadrant.
A graph was a very good representation of the light because it clearly shows the path the light took to the ground, in a way that brings the problem to life. The graph gave a pictorial representation for each value. Y isn’t simply Y its now, the point where the light originated from. And x has a pictorial value as well; X is the place where the beam intersects the ground.
My work was returned to me because I did not find the x value correctly, I do not know how to go about finding this. I have graphed this problem but was not able to send a copy so that you could see my work,
x y=-(2/3)x+30
-1 30 2/3
0 30
1 29 1/3
I need to know what the height is in feet when the laser beam is 30 feet away from the building...
Thank you so much for your help!
Take care
Maranda
1 solutions
Answer 287526 by solver91311(16868) on 2011-02-11 23:36:57 (Show Source):
You can put this solution on YOUR website!
You are way way way over thinking this thing.
Take your equation and substitute 0 in place of x. Do the arithmetic. The value you get for y is the height of the window. Take the original equation and substitute 0 in place of y. Do the arithmetic. The value you get for x is the distance from the building where the beam hits the ground.
John

My calculator said it, I believe it, that settles it
|
Travel_Word_Problems/407877: Noan and Ben are running in the Walker Street Fun Run. Noah runs at 7 mph, Ben at 5 mph. If they start at the same time, how long (in minutes) will it be before they are 1/6 mile apart? 1 solutions
Answer 287400 by solver91311(16868) on 2011-02-11 12:05:07 (Show Source):
|
Triangles/403949: How many right triangles might have a hypotenuse that measures 4x+5 in inches? And legs that measure 3x+13 inches and x inches? What are the dimensions of the triangle? 1 solutions
Answer 285543 by solver91311(16868) on 2011-02-03 17:11:54 (Show Source):
|
|