tricky PS - four quetions.

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tricky PS - four quetions.

by allfta » Tue Jun 08, 2010 3:15 am
Hi guyz.
Would u explain these questions?

1. The points R, T, and U lie on a circle that has radius 4. If the length of arc RTU is 4pai/3, what is the length of line segment RU? anwer) 4


2. If d= 1/2^3 x 5^7 is expressed as a terminating decimal, how many nonzero digits will d have? answer) 2
(I got the answer but just calculate the denominator. other possible convenient approach?)


3.
1)Three pieces of wire have a median length of 48 inches. The other two wires' length are 44 and 48. What is the median?
Is it 48 or 46(median of 44 and 48) or just average? (This question is not a complete one. Sorry)
2)In the same manner, what is the median number of 44 45 45 48 48 ?


4. The operation @ is defined by x@y = 1/x + 1/y for all nonzero numbers x and y. if z is a number greater than 1, which of the following must be true?
1) z @ (-z) = 0
2) z @ z/z-1 = 0
3) 2/z @ 2/z =zd
A 1
B 1,2
C 1,3
D 2,3
E all
I thought it is A but the answelr is D. ur think?


5. is x<y ? (sorry this is DS)
1) the ratio of x to y is 7/9
2) xy>0
answer] E
My question is whether i can represent "the ratio of x to y" to x:y or x/y
And whether I can also use this with - figures.
Source: — Problem Solving |

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by liferocks » Tue Jun 08, 2010 3:20 am
allfta wrote:Hi guyz.
Would u explain these questions?

1. The points R, T, and U lie on a circle that has radius 4. If the length of arc RTU is 4pai/3, what is the length of line segment RU?
2*pi*4 arc lenght makes an angle of 360 degree at center of the cisrcle
so 4pai/3 arc lenght makes an angle of 360*4pi/(3*2*pi*4) or 60 degree
so R,U and the center of circle makes an equilateral triangle hence length of RU=4
"If you don't know where you are going, any road will get you there."
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by liferocks » Tue Jun 08, 2010 3:22 am
allfta wrote:2. If d= 1/2^3 x 5^7 is expressed as a terminating decimal, how many nonzero digits will d have?
d= 1/2^3 x 5^7
=1/(2*5)^3 * 25*25
=(1/1000)*(4/100)*(4/100)
=16/10000000

so non zero digits are 1 and 6..ans 2
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by liferocks » Tue Jun 08, 2010 3:23 am
allfta wrote:Three pieces of wire have a median length of 48 inches. The other two wires' length are 44 and 48. What is the median?
Is it 48 or 46(median of 44 and 48) or just average? (This question is not a complete one. Sorry)
2)In the same manner, what is the median number of 44 45 45 48 48 ?
median is the middle number when numbers are put in ascending order
so for 44 48 48 median is 48
44 45 45 48 48-->median 45
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by liferocks » Tue Jun 08, 2010 3:30 am
allfta wrote:The operation @ is defined by x@y = 1/x + 1/y for all nonzero numbers x and y. if z is a number greater than 1, which of the following must be true?
1) z @ (-z) = 0
2) z @ z/z-1 = 0
3) 2/z @ 2/z =zd
A 1
B 1,2
C 1,3
D 2,3
E all
lets take z=3/2 so -z=-3/2..so z @ (-z) =2/3 - 2/3=0..correct
z/z-1 =3/2 / 3/2-1 =3 so z @ z/z-1 =2/3 +3 =11/3..incorrect
for 3 not sure what is d
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by liferocks » Tue Jun 08, 2010 3:36 am
allfta wrote: is x<y ? (sorry this is DS)
1) the ratio of x to y is 7/9
2) xy>0
from 1 we get x=7k and y=9k so depending on whether k>0 or k<0 x>y or x<y..insufficient
from 2 we get both x,y has same sign..nothing can be concluded..insufficient

ans option E
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by allfta » Sat Jun 12, 2010 8:43 pm
Thank you liferocks!
U r the man.