Re: [計量] 好多題計量請教
※ 引述《balance9235 (退伍變米蟲)》之銘言：
: 1. If M is 30% of Q, which in turn is 20% of P, and N is 50% of P, then the
: ratio of M to N is
: (A) 3/250
: (B) 3/25
: (C) 1
: (D) 6/5
: (E) 4/3 ANS:(B)
M=0.3*Q=0.2*0.3P=0.06P, N=0.5*P
M/N=0.06P/0.5P=3/25
: 2. 1 < a < b < 2
: Column A Column B
: ab a+b ANS:B
: 3. If a, b, and c are the number selected from the set of {1,2,3,4,5}
: with replacement, what is the probability that the value of ab+c will be
: even?
: (A) 2/5
: (B) 59/125
: (C) 7/25
: (D) 64/125
: (E) 3/5 ANS:(B)
abc的組合有：偶偶偶、偶奇偶、奇偶偶、奇奇奇
A=(2^3+2*3*2+3*2*2+3^3)/5^3
=59/125
: 4. An obtuse triangle has sides of lebgths of 11, 15, and k, where k is an
: integer.
: Column A Column B
: The number of 13
: values of k. ANS:C
: 5. If f(x) = x^(x+1)*(x+2)^(x+3), then f(0)+f(-1)+f(-2)+f(-3) is
: (A) -8/9
: (B) 0
: (C) 8/9
: (D) 1
: (E) 10/9 ANS:(E)
f(0)和f(-2)都等於0，可以不用看
f(-1)+f(-3)=1+1/9=10/9
: 6. For function f(n){n+3, n is odd , where n is a positive intege. If k is an
: n/2, n is even
: odd number, and f(f(f(k)))=27, then what is the sum of digits of k?
: (A) 3
: (B) 6
: (C) 9
: (D) 12
: (E) 15 ANS:(B)
f(k)=k+3 is even
f(k+3)=(k+3)/2 is odd or even
f((k+3)/2)=(k+3)/2+3=27 or f((k+3)/2)=(k+3)/4=27
k=57 or 105
但57代回會後=15=/=27，所以k=105
: 7. If E(n) represents the sum of even digits of n, for example, E(5681)=6+8=14
: then E(1)+E(2)+E(3)+...+E(100) is
: (A) 200
: (B) 360
: (C) 400
: (D) 900
: (E) 2250 ANS:(C)
個位數: (2+4+6+8)*10
十位數: (2+4+6+8)*10
總共加起來等於400
: 8. A fair die of six faces is tossed three times repeatedly. If the sum of the
: number of dots from the first two times is equal to the number of dots from
: the third time, then what the probability that at least one of the three
: successive tosses will get 2 dots?
: (A) 1/6
: (B) 91/210
: (C) 1/2
: (D) 8/15
: (E) 7/12 ANS:(B)
ab|c的可能分別是
11 | 2
12 21 | 3
13 22 31 | 4
14 23 32 41 | 5
15 24 33 42 31 | 6
我覺得答案應該是8/15 (D)
: 9. Two marbles are drawn without replacement from a jar that contains 1,001
: red marbles and 1,001 green marbles. If Ps represents the probability that
: the two drawn marbles are in the same color, and Pd represents the
: probability that the two drawn marbles are in different colors, what is
: the value of |Ps - Pd|?
: (A) 0
: (B) 1/2002
: (C) 1/2001
: (D) 2/2001
: (E) 1/1000 ANS:(C)
Ps=1/2*1000/2001*2=1000/2001
Pd=1/2*1001/2001*2=1001/2001
: 10. If a is greater than c by 50%, and b is greater than c by 25%, then a is
: greater than b by what percent?
: (A) 20
: (B) 25
: (C) 50
: (D) 100
: (E) 200
a=c*1.5
b=c*1.25
a/b=1.5/1.25=1.2
答案應該是(A) 20%
有錯的話歡迎指正~~
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