GWD-9Q32: D If n is a positive integer, what is the value of the hundreds digit of 30^n? (1) 30^n > 1,000 (2) n is a multiple of 3. 怎么算的呀？
GWD-9Q36: D If x, y, and k are positive numbers such that (x/x+y)(10) + (x/x+y)(20) = k and if x < y, which of the following could be the value of k? answer:18
GWD-7 Q11:A If x is a positive integer, is the remainder 0 when 3^x + 1 is divided by 10? (1) x = 4n + 2, where n is a positive integer. (2) x > 4
Q29:A If 10^50 – 74 is written as an integer in base 10 notation, what is the sum of the digits in that integer?
Q15 B The average (arithmetic mean) of the 5 positive integers k, m, r, s, and t is 16, and k < m < r < s < t. If t is 40, what is the greatest possible value of the median of the 5 integers?
GWD-9Q32: D If n is a positive integer, what is the value of the hundreds digit of 30^n? (1) 30^n > 1,000 (2) n is a multiple of 3.
1.30^n>1000, n=2==>900. so n must be 3 or greater. 27000 when n is 4, anything >4, hundreds is 0. sufficient 2. n is 3, 6, 9, same as above, when n is 3 and greater, hundreds must be 0.
Q11:A If x is a positive integer, is the remainder 0 when 3^x + 1 is divided by 10? (1) x = 4n + 2, where n is a positive integer. (2) x > 4
Q15 B The average (arithmetic mean) of the 5 positive integers k, m, r, s, and t is 16, and k < m < r < s < t. If t is 40, what is the greatest possible value of the median of the 5 integers?
k， m, r, s, t 5x16=80, 80-40=40 k, m, r, s, 40, 假设 1, 2, r, s, 40 40-1-2=37, 37=18+19 so we have: 1, 2, 18, 19, 40。 18 is our greatest median while satisfying that k<m<r<s<t
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发表于 2012-10-19 14:14:34
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