Final answer:
To find the next time buses to Acton and Barton leave at the same time, calculate the least common multiple of their departure intervals, which is 120 minutes. Therefore, the buses will leave together again 2 hours after 9.00 am, at 11.00 am.
Step-by-step explanation:
The question asks when buses to Acton and Barton, which leave every 24 and 20 minutes respectively, will next leave at the same time if they both initially leave at 9.00 am.
To solve this, we need to find the least common multiple (LCM) of 24 and 20, which represents the first time both buses will leave together after 9.00 am.
- First, list the multiples of 24 (24, 48, 72, 96, ...) and 20 (20, 40, 60, 80, ...).
- Identify the smallest common multiple in both lists, which is 120.
- Since 120 minutes is equal to 2 hours, the buses will next leave the station together at 11.00 am.