[計量] 10月數學機經的疑問

作者: chengru (Eric) 看板: GRE_Verbal
標題: [計量] 10月數學機經的疑問
時間: Fri Oct 26 21:35:45 2007

以下幾題數學機經讓我很困擾，請想的出來的同學幫忙解惑，謝謝！

1. 2^(x-y) = 1/64
Col a: x
Col b: y
Ans:?

2. A ranch has horses and ponies. Five-sixths of the ponies have horseshoes.
Half of the ponies with horseshoes are Icelandic. If there are three more horses than ponies, what is the
minimum number of horses and ponies on the ranch?
A) 12
B) 15
C) 27
D) 48
E) 54

Ans: C （我覺得題目給的條件不夠充分，所以算不出來??）

3. A group of 4 pumps are filling a tank. Each of the 3 smaller pumps works
at 2/3rds the rate of the largest pump. If all 4 pumps work at the same time, they should fill the tank in what fraction of the time that
it would have taken the largest pump if it operated alone?
A) 4/7
B) 1/3
C) 2/3
D) 3/4
E) 4/3
Ans: C （我覺得是B）

4. Given Principal amount P,rate of interest was r ,and the amount increase
from 1990 to 1995 and 1995 to 2000 each time by r%. so the total amount was (7/5)p at the end of 2 yrs .

Col A : r
Col B: 20
Ans:B （我覺得題目給的條件不夠充分，所以算不出來??）

5. Which one is larger?
Col A --- prime numbers between 2321 to 3213
Col B--- prime numbers between 2325 to 3221
Ans: B (No idea how this answer comes up)

6. How much interest would accrue over a $4000 loan over 3 months at 8%
annual Simple Interest?
A)$48
B)$96
C)$240
D)$320
E)$80
Ans: A (我覺得是E)

7. Some two huge number 78678 * 669066
what is the sum of the digits in the units and tenth place
a) 12
b) 8
c) 10
d) 6
e) 4
Ans:C （這題我是硬算的，有比較快的方法嗎？）

8. 0<w<x<y<z. If (z*z)-(y*y)+(x*x)-(w*w)=40, then what is the sum of w+x+y+z?
Ans:找不到答案

9. P={1.3, 0.9, 1.5, 1.1}
Q={1.3x, 0.9x, 1.5x, 1.1x}
col a: standard deviation of P
col b: standard deviation of Q
Ans:找不到答案

10. A Line K passes through (3,4) and origin, line L passes through (-3,4) and
origin. Find the angle between the lines.
1)75
2)80
3)90
4)100
Ans:找不到答案

11. 4^n + 4^(n+1) = 5/64 what is n^2 .
a) 36
b) 25
c) 16
d) 9
e) 4
Ans: d (我算不出這個答案)

12. Given X^-1=2/y^2+1
col a : x
col b : y^2/2
Ans: A (我算不出這個答案)

13. A parabola was draw and a point on it was given as P(2,K)and it was cuting
the Y axis at a point below 2 .ie. it was open upwards the distance was asked
between th point P and the point where the parabola cuts th y axis.
a:3
b:7
c:2sqroot(5)
d:2sqroot(7)
e:3sqroot(3)
Ans:找不到答案

14. What is the probability for particular year between 1987 and 1992 to have
53 Sunday?
Ans. 2/7 (我算不出這個答案)

15. Given dat x*=(x-1)/x condition is x<0 not necessary find which of
the following is true?
a)2x*=2(x*)
b)-x*=x*
c)(x-1)*/x=x*...
d)(x*)*=x
Ans:找不到答案

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◆ From: 220.132.163.59
推 vip82:1. 2^(-6)=1/64 x<y  61.64.77.182 10/26 21:45
→ dichotomy:第一題要考慮正負值吧?  59.105.168.14 10/26 21:58
推 dichotomy:2. 他是問最小值 所以1/2*5/6*X 配整數  59.105.168.14 10/26 22:04
→ dichotomy:4.推回去最快 利率20%-->1.44p 大於7/5p  59.105.168.14 10/26 22:29
→ dichotomy:我第一題耍笨了 不好意思^^"  59.105.168.14 10/26 22:40