Brandon runs 100 metres for 5 times. The average time taken for his first three runs is 17.3 seconds. He aims to have an average timing of 14.8 seconds for his five runs.
- What is the average time he needs to take for his 4th and 5th run in order to achieve his aim?
- If he runs 3 seconds faster in one of the five runs, what would be his average time for the five runs?
(a)
Total timing for first three runs
= 3 x 17.3
= 51.9 s
Total timing needed if the average is to be 14.8 s
= 14.8 x 5
= 74 s
Total timing for last two runs to achieve his aim
= 74 - 51.9
= 22.1 s
Average timing for last two runs
= 22.1 ÷ 2
= 11.05 s
(b)
New average
= (74 - 3) ÷ 5
= 14.2 s
Answer(s): (a) 11.05 s; (b) 14.2 s