Question

The first bus leaves at 07:20, then every 15 minutes till 14:50. How many leave before 11:00

Answer 1

15

Explanation:

The number of minutes from 7:20 to 8:00:

N1 = 40 minutes

The number of minutes from 8:00 to 11:00:

N2 = (11 - 8) x 60 = 180 minutes

=> The number of minutes from 7:20 to 11:00:

N = N1 + N2 = 40 + 180 = 220 minutes

Every 15 minutes, a bus leaves.

The number of 15-minute intervals from 7:20 to 11:00:

220/15 = 14.67 = 14

=> The number of buses leave from 7:20 to 11:00:

14 + 1 = 15

(including the 1st bus)

Hope this helps!

Answer 2

15 buses

Explanation:

7:20 1 bus leaves

Then 1 leaves every 15 minutes

35, 50, 05 and 20 4 buses til 8:20

35, 50, 05 and 20 4 buses til 9:20

35, 50, 05 and 20 4 buses til 10:20

35,50 2 buses leave til 11:00

Add them together

1 +4+4+4+2 = 15 buses