A bus service center has 2 feed services that start together at 8 a.m. Bus A leaves at 15 minutes interval, while bus B leaves at 20 minutes interval. On a particular day , how many times do both services leave together from 8 a.m. to 11 a.m.?
Ans 3
Lcm of 15,20 =60
Different between time 8am to 11am = 3 so 60*3=180 by 60 = 3
The LCM is 60.
60 min = 1 hour
Take note of the term "from" in the last part of the question - "...from 8 am to 11 am", and the idea LEAVE TOGETHER. 8 am is counted, so
8 am + 1 hour = 9 am
9 am + 1 hour = 10 am
8 am-9am-10am = 3 times
11 am will not be included because it is the cut off. If the two buses leave again at 11 am, the schedule will now be changed.
However, if the word "from" is replaced by "between" then the answer should be 2 times. The word BETWEEN indicates that the starting point is not included and the end point as well.
9 am and 10 am = 2 times
60......
15 and 20 LCM =60 The time 8 a. m. to 11 a. m.
Lcm of 15 and 20 is 60
The Bus will leave in 60 minutes its 8 am to 11 am
Hcf is 5 rest idk ðŸ˜
Here it will be LCM 20and 15 is 60
So the bus will leave after every 60 minute