Question

Several different bus routes stop at the corner of Second St. and Lincoln Ave. A Wilkenson bus arrives every 21 minutes and a Harris Road bus arrives every 15 minutes. If both buses arrive at the stop at​ 5:07 AM, when will they again arrive at the same​ time?

Answer 1

Both buses will arrive at the stop at 6:52 AM

Explanation:

Wilkenson Bus = Arrives every 21 minutes

Harris Road Bus = Arrives every 15 minutes

Let's find the Least Common Multiple (LCM) of 21 and 15. LCM is found, listing the prime factors of each numbers and then multiplying each factor the greatest number of times it occurs in either numbers:

LCM 21 = 3 × 7

LCM 15 = 3 × 5

LCM (21 , 15) = 3 × 7 × 5 = 105

In 105 minutes both buses will arrive at the same time again

105 minutes = 1 h 45 min

5:07 AM + 1h 45 min = 6:52 AM