[問題]PREP-T2-Q200 Q209 (DS)

[oneseven]

Q200
If d is a positive integer and f is the product of the first 30 positive integers, what is the value of d?

(1) 10^d is a factor of f.
(2) d>6

Answer : C

Q209
The cost of each adult's ticket for a certain concert was $30, and the cost of each child's ticket for the concert was $24. If Hannah puchased tickets for the concert, what was the average cost per ticket?

(1) Hannah purchased twice as many children's tickets as abult's tickets.
(2) Hannah purchased 4 children's tickets.

Answer : A 題目要求的是平均票價 那為何條件2不充分呢

感謝解答

[hey]

第209題
條件一: 請將買小孩票的張數設為2A,而買大人票的張數設為A
則均價為(2A*24+A*30)/2A+A=26
條件二:其只給你他買4張小孩票, 但他沒有跟你說他買了多少張大人票, 你不能假定他沒買, 他只是沒提而已,所以無法求出來

因此選項會是(A)