Bobby jogged at the park once every 3 days. Cody jogged at the same park once every 7 days. They met on 5 November 2021. There are 30 days in November and 31 days in December.
- On which date they next met each other at the park? Give your answer at the following format. (Eg 1 Jan 2000)
- How many times did they meet at the park at November and December 2021?
(a)
Multiples of 3: 3, 6, 9, 12, 15, 18, 21
Multiples of 7: 7, 14, 21
LCM of 3 and 7: 21
Bobby and Cody met every 21 days.
21 days after 5 November 2021 = 26 Nov 2021
The day that they next met at the park = 26 Nov 2021
(b)
Since Bobby and Cody first met on 5 November 2021, they did not meet for the first 4 days of November 2021.
Total number of days from 5 November 2021 to 30 December 2021
= 30 + 31 - 4
= 57
Number of sets of 21 days from 5 November to 30 December 2021
= 57 ÷ 21
= 2 r 15
On the first day of each of the 2 sets of 21 days, they would meet at the park.
Since there is a remainder of 15, this means that on the first day of the remaining 15 days, they would meet at the park again.
Number of times that they met at the park in November 2021 and December 2021
= 2 + 1
= 3
Answer(s): (a) 26 Nov 2021; (b) 3
