New!
Get regular updates about newly solved problems
via algebra.com's RSS system.
Recent problems solved by 'josmiceli'
josmiceli answered: 9642 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, >>NextPermutations/548939: How many ways can a 3-people committee be chosen from 10 twins(20 people)? Restriction: No twins can both exist in this committee. (e.g Assume A & B are twins, if A is in the committee, B cannot be in.) 1 solutions
Answer 357318 by josmiceli(9645) on 2011-12-19 03:48:18 (Show Source):
You can put this solution on YOUR website!The 1st choice is any one of 20
---------
There are 19 left, but one of them is
the twin of the 1st choice, so there
are 18 valid 2nd choices
---------
There are 17 3rd choices, but one of these is
the twin of the 2nd choice, so there are
16 valid 3rd choices
|
Word_Problems_With_Coins/548879: Hakeem has $2.35 in nickels and quarters. He has 23 coins altogether. How many coins of each kind does he have? 1 solutions
Answer 357279 by josmiceli(9645) on 2011-12-18 22:08:10 (Show Source):
You can put this solution on YOUR website!Let  = number of nickels
Let  = number of quarters
given:
(1) 
(2)  ( in cents )
----------------
Multiply both sides of (1) by 5 and subtract (1) from (2)
(2) 
(1)

and, since
(1) 
(1) 
There are 17 nickels and 6 quarters
check:
(2) 
(2) 
(2) 
OK
|
Divisibility_and_Prime_Numbers/548318: a three digit number is divided by a 1 digit number the quotient is a 2 digit number what can you say about the dividend and the divisor ? 1 solutions
Answer 356937 by josmiceli(9645) on 2011-12-16 21:48:50 (Show Source):
You can put this solution on YOUR website!xxx / x = xx
also,
xxx = xx * x
The 1-digit number can't be 1
If it is 2, then the 2-digit number
must be 50 or greater.
3-digit must be 100 or greater
------------------------
If it is 3, the 2-digit number must be
34 or greater. 3-digit is 102 - 297
--------------
If it is 4, the 2-digit number must be
25 or greater. 3-digit is 100 -396
--------------
If it is 5, the 2-digit number must be
20 or greater. 3-digit is 100 - 495
-------------
If it is 6, the 2-digit number must be
17 or greater. 3-digit is 102 - 594
-------------
If it is 7, the 2-digit number must be
15 or greater. 3-digit is 105 - 693
------------
If it is 8, the 2-digit number must be
13 or greater. 3-digit is 104 - 792
------------
If it is 9, the 2-digit number must be
12 or greater. 3-digit is 108 - 891
|
Coordinate-system/548303: what's he distance between this points (-3,4),(1,-1), i tried to get it solved with the formula, but it seems that in the book it's done in the wrong way thank for helping. 1 solutions
Answer 356882 by josmiceli(9645) on 2011-12-16 16:53:40 (Show Source):
|
Rate-of-work-word-problems/548284: How long will it take someone running at 12 mph to catch up to someone walking at 5 mph with an hour and a half head start?
I'm thinking that I can set up a system of equations and figure it out from there, but I can't figure out how to set it up. help please!
Thank-you! 1 solutions
Answer 356863 by josmiceli(9645) on 2011-12-16 14:27:09 (Show Source):
You can put this solution on YOUR website!
 mi
The 5 mi/hr walker has a 7.5 mi head start
Start a stopwatch when the 12 mi/hr runner starts
It will now take them both the same amount of time
until they meet. Call this time 
Runner's equation:
(1) 
Walker's equation:
(2) 
(2) 
(2)  hrs

It will take the runner 1 hr and 4 min to catch walker
Really strange numbers, hope I got it right
|
Miscellaneous_Word_Problems/548244: I have a tank that can be filled by a small pipe in 12 hours or by a large pipe in 8 hours. Suppose I start filling the tank with the large pipe for two hours. After that 2 hours is up, I use both pipes and continue filling the tank for a length of time, t. I then turn off the large pipe and it takes 2 more hours to fill the tank with just the small pipe. How long of a time is t? 1 solutions
Answer 356855 by josmiceli(9645) on 2011-12-16 13:42:24 (Show Source):
You can put this solution on YOUR website!In words:
( portion of the tank filled ) = ( rate of filling ) x ( time spent filling )
Rate using small pipe: ( 1 tank ) / ( 12 hrs )
Rate using large pipe: ( 1 tank ) / (8 hrs )
----------------------------------
Using large pipe for 2 hrs:
Portion of tank filled is 
There is  of the tank left to be filled
----------------------------------
Using both pipes, add their rates of filling
to get rate together

Now the fraction of the tank left to be filled
is 
------------------
Using the small pipe for 2 more hrs
 hrs
 min
 is 2 hrs and 48 min
I may have made a mistake, but
I think the method is good
|
Equations/548227: This is a system of equation problem and I am not sure what I need to do as we are just starting them. Could you please help me out? The question is How many days before 17th August is it, if 50 days ago it was four times as many since March 30th? 1 solutions
Answer 356814 by josmiceli(9645) on 2011-12-16 10:37:03 (Show Source):
You can put this solution on YOUR website!Let  = number of days before August 17
-------------------------------------
given:
 days before August 17 it was
 days since March 30
-------------------------
 = number of days between
March 30 and August 17
---------------------
March 31 = 1 day
April has 30 days
May has 31
June has 30
July has 31
There are 16 days before August 17

I'll call it 18 days
check:
August 17 minus 18 days is July 31
July 31 minus 50 days is June 10
---------------------------

Is it 72 days since March 30?
 days
---------------------------
I believe 18 days is the answer, but I lost
1 day somehow in my calculations
|
Miscellaneous_Word_Problems/548143: if a person takes 10 hours to clean his room. It takes his mother 5 hours to clean his room. If that person starts cleaning a 1pm and his mother starts helping at 2pm, at what time will it take the room to be clean? 1 solutions
Answer 356735 by josmiceli(9645) on 2011-12-15 23:29:20 (Show Source):
You can put this solution on YOUR website!First find the fraction of the room that
person cleans from 1 PM to 2 PM
Person's rate = ( 1 room ) / ( 10 hrs )

Person cleans 1/10 of the room in 1 hr
There is 9/10 of the room left to clean
-------------------------------
Add their rates.
Let  = time for both to finish room
With person and Mother both cleaning:

Multiply both sides by
 hrs
The room will be clean in  hrs
4 hrs from 1 pm is 5 pm
|
Rate-of-work-word-problems/548134: At 10:00 a.m. pipe A began to fill an empty storage tank. At noon, pipe A malfunctioned and was closed. Pipe B was used to finish filling the tank. If pipe A needs 6h to fill the tank alone and pipe B needs 8h, at what time was the tank full? 1 solutions
Answer 356733 by josmiceli(9645) on 2011-12-15 23:17:15 (Show Source):
You can put this solution on YOUR website!First find out how much of the tank by
pipe A alone
10 AM to noon is 2 hrs
Pipe A's rate is ( 1 tank )/( 6 hrs )
 of a tank
------------------------
There is 2/3 of the tank left to fill
Let  = time in hrs for B to finish filling tank
B's rate is ( 1 tank ) / ( 8 hrs )
Multiply both sides by

The time used by both pipes is 
This is 7 hrs and 20 min to fill the tank
|
test/548133: solve by substitution
2x + 4y = 8
-2x + y = 12 1 solutions
Answer 356726 by josmiceli(9645) on 2011-12-15 22:54:41 (Show Source):
You can put this solution on YOUR website!(1) 
(2) 
---------------
Divide both sides of (1) by 
(1) 
(1) 
----------------
Substitute (1) into (2)
(2) 
(2) 
(2) 
(2) 
--------------
And, since
(2) 
(2) 
(2) 
(2) 
--------------
The solution is ( -4, 4 )
check answer:
(2) 
(2) 
(2) 
(20 
OK
and
(1) 
(1) 
(1) 
(1) 
OK
|
Age_Word_Problems/547974: Lewis and Vernon are 152 miles apart. A car leaves Lewis headed toward Vernon, and another car leaves Vernon at the same time headed towards Lewis, the car leaving Lewis averages 10mph more than the other and they meet after 1hr and 36 min. what are the average speeds of the cars? 1 solutions
Answer 356668 by josmiceli(9645) on 2011-12-15 18:17:42 (Show Source):
You can put this solution on YOUR website!Let  = speed of car leaving Vernon
 = speed of car leaving Lewis
You can add their speeds to get speed of approach
 hrs
1 hr 36 min =  hrs

The speed of car leaving Vernon is 42.5 mi/hr
The speed of car leaving Lewis is 52.5 mi/hr
|
Word_Problems_With_Coins/547950: Hi, I tried this question out a bunch of times, but I can't find the answer. Here is the question: "Mark has 26 nickels, dimes and quarters, altogether totaling $3.00. He has twice as many dimes as
nickels. Find the number of each coin that he has"
And I was taught not to do q for quarters, d for dimes, or n for nickels. here is an example.
" A student has $5.90 in dimes and quarters. There are 32 coins altogether. How many of each coin
does the student have?"
the let statements I would write would be:
Let x= dimes
Let 32-x= quarters.
Sorry if this is confusing but I would like if you could try to help. You can do the q, d, or n, but if you could do it the way i learned it that would really help. 1 solutions
Answer 356662 by josmiceli(9645) on 2011-12-15 17:43:16 (Show Source):
You can put this solution on YOUR website!I personally like the q,d,n method but I can do it
the other way, too.
There are 26 coins, and it is given:
 , so I now have
 ,
 , so now I have
n, 2n, 26 - 3n instead of n, d, and q
Now I can say
 ( all in cents )

and, there are  dimes, so

and
 quarters
There are 7 nickels, 14 dimes, and 5 quarters
check answer:

OK
|
Rate-of-work-word-problems/547938: Ok i am not understanding this question . A sightseeing boat makes 4 trips each day. It travels 9 miles on each trip. How many miles does it travel in 6 days ? 1 solutions
Answer 356658 by josmiceli(9645) on 2011-12-15 17:08:03 (Show Source):
You can put this solution on YOUR website!the boat makes 4 trips/day
( 4 trips/day ) x ( 9 mi/trip ) = 36 mi/day
( 9 mi/day )x ( 6 days ) = 54 mi
-------------------------
can you see how the units cancel?
( trips/day ) x ( mi/trip ) = mi/day
Notice how the trips cancel
|
decimal-numbers/547914: One problem on my homework is "It took 86 hours for joe kittinger
To cross the Atlantic in his ballon, Rosie O'Grady, a distance of 3543 miles.
What was the average speed of the ballon ? Round to the nearest tenth ."
So i tried to divide 3543 by 86 and came up with 41.1976744 but it seems
Kind of impossible to round to the nearest tenth . Can you help please ?
Thank You ! 1 solutions
Answer 356651 by josmiceli(9645) on 2011-12-15 16:32:47 (Show Source):
You can put this solution on YOUR website! ( rounded to nearest tenth )
This problem gets into the subject of
" significant figures "
Actually, not all the digits after the decimal point are
really " significant ".
Notice the hours is 86 and not 86.3, or 85.9, so
86 is as close as can be judged
That is 2 significant figures.
3543 has 4 significant figures. They could have said
3543.27. That would have been 6 significant figures
--------------------
The number of significant figures in the answer is
determined by the least accurate number in the input data,
so really only 2 figures in answer can be relied on.
So 3 figures is just fine
|
Graphs/547910: Write the equation for the following situation: In one U.S. town, the annual consumption, s, of sugar (in kg per person) can be estimated by adding 30 to half the years, t, since 1975.
Then graph the equation and use the graph to determine the sugar consumption in the year 1991. 1 solutions
Answer 356650 by josmiceli(9645) on 2011-12-15 16:19:53 (Show Source):
You can put this solution on YOUR website!given:

here's the plot:
 is plotted on the vertical axis
 is plotted on the horizontal axis
Go to  since 1975 + 16 = 1991
 looks like about
|
Rate-of-work-word-problems/547846: one pipe can fill a tank in 12 hours, and another can fill the tank in 8 hours. how long will it take both pipes working together to fill the tank? 1 solutions
Answer 356597 by josmiceli(9645) on 2011-12-15 13:56:03 (Show Source):
You can put this solution on YOUR website!Add their rates of filling
1st pipe's rate = ( 1 tank ) / ( 12 hrs )
2nd pipe's rate = ( 1tank ) / ( 8 hrs )
Let  = hrs to fill tank using both pipes

Multiply both sides by

It will take 4 hrs and 48 min with both pipes
|
|