Question

提问几道GRE数学题!都是绿皮上的,本人数学不大好,P275.39In how many of the integers

Answer 1

题目是问在1和100之间的整数中,有多少个5只出现1次.

5,15,25,35,45,65,76,85,95

50,51,52,53,54,56,67,58,59,共18个(55不算)

The total distance is 60*3 + 45*2 = 270 miles,total time is 5 hours,evarage speed is 270/5 = 54 mph

27*4 = 108 students < 110,5 classes are needed.