Problem 1.
(1) n = 6, 9
i.e. n can be odd or even. Therefore, (1) is insufficient.
(2) n = 9, divisor = 1,3,9
2n = 18, divisor = 1,2,3,6,9,18
n = 15, divisor = 1,3,5,15
2n = 30, divisor = 1,2,3,5,6,10,15,30
i.e. n should be odd. Therefore, (2) is sufficient.
Answer should be (2).
Problem 3.
Distance travelled by cyclist in 5 mins = 20*5/60 = 5/3 miles
Time taken by hiker to tranvel 5/3 miles = (60/4)*(5/3) = 25 mins
Total wait time for cyclist = 25 - 5 = 20 mins
Answer should be ©.