Question

(viii) The local bus service has 2 lines of buses that start together at 8 a.m. Buses on line A leave after every 15 minutes while Buses on line B leave after every 20 minutes. In a day, how many times do buses on both line A and B leave together between 8 a.m. and 11 a.m?​

Answer 1

Answer:

2 times

Step By Step Explanation:

LCM of 15 and 20 = 60

First time they meet at 9 AM

Second time they meet at 10 AM'

So, they meet 2 times

Answer 2

Given data:

• The local bus service has 2 lines of buses that start together at 8 a.m.
• Buses on line A leave after every 15 minutes while Buses on line B leave after every 20 minutes.

To find:

In a day, how many times do buses on both line A and B leave together between 8 a.m. and 11 a.m?

Step-by-step explanation:

In order to find our solution, we have to find the LCM of 15 and 20.

Here 15 = 3 × 5

and 20 = 2 × 2 × 5

So, required LCM = 2 × 2 × 3 × 5 = 60

• 60 minutes = 1 hour

So the buses leave together after 1 hour.

8 a.m. + 1 hour = 9 a.m.

9 a.m. + 1 hour = 10 a.m.

Final answer:

In a day, two times, the buses leave on both line A and B together between 8 a.m. and 11 a.m.

NOTE:

If we count 8 a.m. and (10 a.m. + 1 hour) = 11 a.m., then in the time 8 a.m. - 11 a.m., the buses leave four times together.