See tutors' answers!

Algebra ->  Tutoring on algebra.com -> See tutors' answers!      Log On


   
By Tutor
 | By Problem Number | 

Tutor:
New! Get regular updates about newly solved problems via algebra.com's RSS system.

Recent problems solved by 'rfer'

rfer answered: 12674 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, >>Next

Equations/454016: One foot of one-eighth inch copper wire weights four ounces. What is the weight of five-eighths miles of this tubing? Note: one mile=5,280 feet.
1 solutions
Answer 311827 by rfer(12678) About Me  on 2011-05-25 13:57:23 (Show Source):
You can put this solution on YOUR website!
1/4=3168/x
x=12672 oz
x=792 lbs

Trigonometry-basics/453696: Suppose John draws a card from a standard deck of cards. What is the probability that he draws a heart or an ace.
(1) 12/52 (2) 16/52 (3) 18/52 (4) 17/52

I was stuck because i thought that there are 4 types of symbols in cards, hearts spades, clover, and diamond. So to find the probability of only hearts or an ace it must be 4*4 ? or 4*2? in total i know there is 52 cards.
1 solutions
Answer 311691 by rfer(12678) About Me  on 2011-05-24 20:30:45 (Show Source):
You can put this solution on YOUR website!
13 hearts plus the three other aces
16/52

Equations/453708: Can someone help me simplify this problem?
∛216
1 solutions
Answer 311688 by rfer(12678) About Me  on 2011-05-24 20:28:07 (Show Source):

Linear-systems/453618: How do I solve a linear equation if the y is listed first? For example
-4Y-3x=-4
1 solutions
Answer 311651 by rfer(12678) About Me  on 2011-05-24 17:27:01 (Show Source):
You can put this solution on YOUR website!
It makes no difference the order as long as you remember that when making an input/output table the x is always listed first and the x is always first in an ordered pair.
you can also change the equation to the "slope/intercept" form.
-4y=3x-4
y=-3/4+1
slope m=-3/4
y int b=1

Travel_Word_Problems/453549: How long will it take to drive 963 miles going 65 mph
1 solutions
Answer 311639 by rfer(12678) About Me  on 2011-05-24 16:00:25 (Show Source):
You can put this solution on YOUR website!
t=D/r
t=963/65
t=14.8 hrs
t=14 hrs 48 minutes

Polynomials-and-rational-expressions/453575: Express each number in scientific notation.

12. 46,300




13. 0.003592




14.284*10 ^3




15.52.8*10^-9


1 solutions
Answer 311637 by rfer(12678) About Me  on 2011-05-24 15:57:46 (Show Source):
You can put this solution on YOUR website!
4.63x10^4
3.592x10^-3
1.4284x10^4
1.5528x10^-8

Equations/453356: write an equation which says that distance d equals the product of rate of travel r and time traveled t
1 solutions
Answer 311503 by rfer(12678) About Me  on 2011-05-23 23:53:58 (Show Source):

Money_Word_Problems/453362: If c dollars are deposited in an account paying R% annual interest, the amount after x years is A=C(1+r)^x. Approximate the amount of the account after x years when C=$100, r=16% and x=21 yrs
I thank-you
1 solutions
Answer 311502 by rfer(12678) About Me  on 2011-05-23 23:52:38 (Show Source):
You can put this solution on YOUR website!
A=100(1.16)^21
A=100*22.57
A=$2257.00

real-numbers/453341: Estimate: 700+822
1 solutions
Answer 311501 by rfer(12678) About Me  on 2011-05-23 23:49:32 (Show Source):

Radicals/453343: what is the square root of the fraction 50/32?

1 solutions
Answer 311500 by rfer(12678) About Me  on 2011-05-23 23:48:28 (Show Source):

Numeric_Fractions/453344: How do you write the square root of 226 in its lowest term?
1 solutions
Answer 311498 by rfer(12678) About Me  on 2011-05-23 23:46:09 (Show Source):

real-numbers/453338: True or false: (a+b)+c=a+(b+c)
1 solutions
Answer 311484 by rfer(12678) About Me  on 2011-05-23 22:09:50 (Show Source):

Miscellaneous_Word_Problems/453332: I don't know where to go so that's why I came here.
The current I in an electrical conductor varies inversely as the resistance R of the conductor. The current is 9 amperes when the when the resistance is 920 ohms. What is the current when the resistance is 560 ohms.
Preciate it.
1 solutions
Answer 311483 by rfer(12678) About Me  on 2011-05-23 22:09:10 (Show Source):
You can put this solution on YOUR website!
use E=IR
E=9*920
E=8280 volts
---------------
I=E/R
I=8280/560
I=14.8 Amps
Is this what you were looking for?
Bob Certified Electronic Technician

test/453282: (3/4-2/3)+(1/2+1/3)
1 solutions
Answer 311448 by rfer(12678) About Me  on 2011-05-23 20:35:53 (Show Source):
You can put this solution on YOUR website!
9/12-8/12+6/12+4/12=11/12

Radicals/453261: i need help solving this problem:
(x+3.25)2=(x-4.1)2
this is what i have so far:
(x+3.25)(x+3.25)=(x-4.1)(x-4.1)
1 solutions
Answer 311426 by rfer(12678) About Me  on 2011-05-23 19:15:29 (Show Source):
You can put this solution on YOUR website!
x^2+3.25x+3.25x+10.56=x^2-4.1x-4.1x+16.81
x^2+6.5x+10.56=x^2-8.2x+16.81
The x^2's cancel.
14.7x=6.25
x=6.25/14.7
x=0.425

logarithm/453210: If Emery has $1700 to invest at 11% per year compounded monthly, how long will it be before he has $2800? If the compounding is continuous, how long will it be? (Round your answers to three decimal places.)
A. 57.128 yrs, 4.718 yrs
B. 0.398 yrs, 0.378 yrs
C. 3.391 yrs, 0.454 yrs
D. 4.557 yrs, 4.536 yrs


1 solutions
Answer 311425 by rfer(12678) About Me  on 2011-05-23 18:48:24 (Show Source):
You can put this solution on YOUR website!
D)
A=1700(1+0.11/12)^(12*t)
A=1700(2.7183)^(0.11*t)

Linear-equations/453248: how would you write the equation 4y-3=5x in standard form?

1 solutions
Answer 311424 by rfer(12678) About Me  on 2011-05-23 18:45:50 (Show Source):

Linear-equations/453252: write an equation in slope intercept form that describes the line with a slope of 4 and the y-intercept of 1.
1 solutions
Answer 311423 by rfer(12678) About Me  on 2011-05-23 18:44:01 (Show Source):

Linear-equations/453250: find the slope of 4x+y=8.

1 solutions
Answer 311422 by rfer(12678) About Me  on 2011-05-23 18:43:22 (Show Source):
You can put this solution on YOUR website!
y=-4x+8
slope m=-4

Polynomials-and-rational-expressions/453208: Parabolas
Determine the vertex of the given equation.
y = -x2 + 4x - 4

1 solutions
Answer 311421 by rfer(12678) About Me  on 2011-05-23 18:42:32 (Show Source):

Angles/453240: one angle is 15 degree less than its complement.Find both measures?
1 solutions
Answer 311420 by rfer(12678) About Me  on 2011-05-23 18:37:53 (Show Source):
You can put this solution on YOUR website!
x+x-15=90
2x=105
x=52.5
x-15=37.5

Equations/453243: 12(x-1)-3(x-1)
1 solutions
Answer 311419 by rfer(12678) About Me  on 2011-05-23 18:36:10 (Show Source):
You can put this solution on YOUR website!
12x-12-3x+3=9x-9

Money_Word_Problems/453216: $1000 is invested at 5% compounded monthly. to how much money will that grow in 10 years?how much will it be if interest is compounded continously?
1 solutions
Answer 311418 by rfer(12678) About Me  on 2011-05-23 18:34:58 (Show Source):
You can put this solution on YOUR website!
A=1000(1+0.05/12)^12*10
A=1000(1.00417)^120
A=1000*1.6477
A=1647.65
--------------------
A=1000(2.7183)^0.05*10
A=1000*1.6487
A=1648.73

test/453224: 6(1-5m)
1 solutions
Answer 311415 by rfer(12678) About Me  on 2011-05-23 18:26:31 (Show Source):

Expressions-with-variables/453226: -7a+2/3(12a+15)-10 simplify
^
fraction
1 solutions
Answer 311414 by rfer(12678) About Me  on 2011-05-23 18:25:37 (Show Source):
You can put this solution on YOUR website!
-7a+8a+10-10=a

Exponential-and-logarithmic-functions/452859: what does x equal?
log 10,000=x
1 solutions
Answer 311215 by rfer(12678) About Me  on 2011-05-22 21:18:13 (Show Source):

Probability-and-statistics/452794: For the table that follows, answer the following questions:
x
y
1 -6
2 -10
3 -14
4


- Would the correlation between x and y in the table above be positive or negative?

- Find the missing value of y in the table. would this be -18?

- How would the values of this table be interpreted in terms of linear regression?

- If a "line of best fit" is placed among these points plotted on a coordinate system, would the slope of this line be positive or negative?

1 solutions
Answer 311214 by rfer(12678) About Me  on 2011-05-22 21:17:10 (Show Source):
You can put this solution on YOUR website!
A)
Negative
B)
-18
C)
You do this one
D)
Negative

Geometry_Word_Problems/452854: in a rectangle, the ratio of the width to the length is 4:5. if rectangle is 40 centimeters long, find its width
1 solutions
Answer 311212 by rfer(12678) About Me  on 2011-05-22 21:08:30 (Show Source):
You can put this solution on YOUR website!
4/x=5/40
5x=160
x=32 cm

Sequences-and-series/452853: Viola makes gift baskets for valintines day. She has 5 baskets left over from last and she plans to make 6 more each day. If there are 17 work days until the day she begins to sell the baskets, how many baskets will she have to sell?
1 solutions
Answer 311210 by rfer(12678) About Me  on 2011-05-22 21:06:53 (Show Source):

Exponential-and-logarithmic-functions/452710: how do would you solve this problem g3/4=8
1 solutions
Answer 311201 by rfer(12678) About Me  on 2011-05-22 20:10:15 (Show Source):
You can put this solution on YOUR website!
g^3=8*4
g^3=32
g=3.175

Volume/452727: Find the slope-intercept form the equation of the line that passes through the point (3,-9) and has slope -1.
1 solutions
Answer 311199 by rfer(12678) About Me  on 2011-05-22 20:07:45 (Show Source):
You can put this solution on YOUR website!
-9=-1*3+b
-9=-3+b
b=-6
-------------
y=-x-6