Need explanation some prob 4m BIG book

[sarkar]

hi frnds, I will take my GRE exam. on the last week of sept and it will be really helpful for my side, if anyone explain the following The GRE Big Book question(apologize if the following question was clarify before).

1. Two tanks, X and Y , are filled to capacity with jet fuel, Tank X holds 600 gallons more than tank Y. If 100 gallons of fuel were to be pumped from each tank, tank X would then contain 3 times as much fuel as tank Y. What is the total number of gallons of fuel in the two full tanks?

a) 1400.(ANS)
b) 1200.
c) 1000.
d) 900.
e) 800.


2. If the value of the expression above is to be halved by doubling exactly one of the five numbers a,b,c,d or e, which should be doubled?
a)a,
b)b,
c) c,
d) d,(Ans)
e)e,


3. if r & s r positive integers, each greater than 1, if 11(s-1)=13(r-1), what is the least possible value of r+s?.

a) 2.
b) 11.
c) 22.
d) 24.
e) 26.(Ans).

4. The rectangular solid(RapidShare: Easy Filehosting), is made of eight cubes of the same size , each of which has exactly one face painted blue. What is the greatest fraction of the total surface area of the solid that could be blue.(bb_test 9_section3_28)

a) 1/6.
b) 3/24.
c) 1/4.
d) 2/7.(Ans)
e) 1/3.

5) If the figure(RapidShare: Easy Filehosting) is a rectangular solid composed of cubes, each with edge of length 4 centimeters, what is the volumn of the rectangular solid in cubic centimeters?(bb_test 9_section5_28).

a) 100.
b) 256.
c) 400.
d) 5120.
e) 6400.Ans)

6) A cyclist travels x miles in w hours & z minusted. What is the cyclists speed in miles per hours?

a) x/(w+60z).
b) (6ow+z)/x
c) 60x/(w+z).
d) 60x/(6ow+z).(ANS)

7) The integers between 1 and 100, inclusive, are put in list A if they are divisible by 2 & in list B if they are divisible by 3. How many inegers in list A are not in list B.

a) 11.
b) 16.
c) 25.
d) 33.
e) 34.(Ans)

8) Each of the following numbers has two digits # out. Which of he numbers could be the numbers of hours in x days, where x is an integer?


Ans: 65#,# 20

9) A large square( 8 inches by 8 inches) formed by fitting three L- shaped tiles and one small square tiles together. If the rectangular floor 10 feet by 12 feet is to be tiled in large square of this design , how many L-shaped tiles will be needed?.

Ans:810.
[IMG]file:///C:/DOCUME%7E1/Sekhor/LOCALS%7E1/Temp/moz-screenshot-1.jpg[/IMG][IMG]file:///C:/DOCUME%7E1/Sekhor/LOCALS%7E1/Temp/moz-screenshot-2.jpg[/IMG] [IMG]file:///C:/DOCUME%7E1/Sekhor/LOCALS%7E1/Temp/moz-screenshot.jpg[/IMG]

[FilleNouvelle]

1) Use the info given...

X holds 600 gallons more than Y...X=Y+600
When 100 gallons are taken from each tank, X has 3 times more...X-100= 3(Y-100)

You end up with 2 equations:
X=Y+600
X=3Y-200

Set them equal Y+600 = 3Y-200. Solving for Y, you get Y=400, plug it back in to get X= 1000. 1000+400=1400.

[mewidyu]

2. If the value of the expression above is to be halved by doubling exactly one of the five numbers a,b,c,d or e, which should be doubled?
a)a,
b)b,
c) c,
d) d,(Ans)
e)e,

what is above question?

[mewidyu]

7) The integers between 1 and 100, inclusive, are put in list A if they are divisible by 2 & in list B if they are divisible by 3. How many inegers in list A are not in list B.

a) 11.
b) 16.
c) 25.
d) 33.
e) 34.

list A=
2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36, 38,40,42,44,46,48,50
,52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,8 4,86,88,90,92,94,96,98,100

list B=
3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48
,51,54,57,60,63,66,69,72,75,78,81,84,87,90,93,96,9 9

so the integers in list A which are not divided by 3=
2,4,8,10,14,16,20,22,26,28,32,34,38,40,44,46,50
,52,56,58,62,64,68,70,74,76,80,82,86,88,92,94,98,1 00

so there will be total of 34 integers...

[mewidyu]

A cyclist travels x miles in w hours & z minusted. What is the cyclists speed in miles per hours?

a) x/(w+60z).
b) (6ow+z)/x
c) 60x/(w+z).
d) 60x/(6ow+z).

w hours and z mins= w hours +z/60 hours= w+z/60 hrs
so the speed will be = distance/ time
= x / (w+z/60)
after solving we get..
= 60x/(60w+z)

[mewidyu]

3. if r & s r positive integers, each greater than 1, if 11(s-1)=13(r-1), what is the least possible value of r+s?.

a) 2.
b) 11.
c) 22.
d) 24.
e) 26.(Ans).

to satisfy the equation we must put value s-1=13 and r-1=11 (11*13=13*11)

so s-1=13 then s=14
r-1=11 then r=12

so r+s= 26

[mewidyu]

4. The rectangular solid(RapidShare: Easy Filehosting), is made of eight cubes of the same size , each of which has exactly one face painted blue. What is the greatest fraction of the total surface area of the solid that could be blue.(bb_test 9_section3_28)

a) 1/6.
b) 3/24.
c) 1/4.
d) 2/7.(Ans)
e) 1/3.

but as i think answer will be 1/3
look it here..
http://www.urch.com/forums/gre-math/...e-problem.html (cube problem)

[mewidyu]

5) If the figure(RapidShare: Easy Filehosting) is a rectangular solid composed of cubes, each with edge of length 4 centimeters, what is the volumn of the rectangular solid in cubic centimeters?(bb_test 9_section5_28).

a) 100.
b) 256.
c) 400.
d) 5120.
e) 6400.Ans)

1st approach...
as there are total of 5*5*4 i.e. 100 cubes so the volume if the rectangular solid will be 100 times the volume of the single cube...
= 100*4*4*4=6400 cc

2nd approach
length of the rectangular solid= 4 cm*5 = 20cm
breadth of the rectangular solid = 4 cm*4 = 16cm
height of the rectangular solid = 4 cm*5 = 20 cm

so the area of the rectangular solid will be 20*16*20=6400 cc

[mewidyu]

1. Two tanks, X and Y , are filled to capacity with jet fuel, Tank X holds 600 gallons more than tank Y. If 100 gallons of fuel were to be pumped from each tank, tank X would then contain 3 times as much fuel as tank Y. What is the total number of gallons of fuel in the two full tanks?

a) 1400.(ANS)
b) 1200.
c) 1000.
d) 900.
e) 800.

from the first line....
x=y+600
from the second line
x-100=3(y-100)

after solving this we get
y= 400
x=400+600=1000
so the total capacity will be 400+1000=1400 gallon


yu can find the same question in the thread below... check the question- 9 and its explanation..
http://www.urch.com/forums/gre-math/...ion-bb-qs.html (Need explanation for BB q's)

[mewidyu]

9) A large square( 8 inches by 8 inches) formed by fitting three L- shaped tiles and one small square tiles together. If the rectangular floor 10 feet by 12 feet is to be tiled in large square of this design , how many L-shaped tiles will be needed?.

area of the large square= 8*8=64 sqr inch
area of the rectangular floor= 10*12*12*12=17280 sqr inch
so in the rectangular floor there will be total of 17280/64=270 tiles...
as in one tile there are 3 L-shaped tiles so there will be total of 270*3=810 tiles