The table shows the time taken by Jack to run 100 metres during his training sessions. After 3 attempts, Jack wanted to improve his average time taken by 1.1 seconds by running faster in the 4
th attempt. How fast should he run in the 4
th attempt in order for him to make the improvement?
Attempt |
1st |
2nd |
3rd |
4th |
Time taken (in seconds) |
22 |
15 |
23 |
? |
Total time that Jack took for the first 3 attempts
= 22 + 15 + 23
= 60 s
Average time that Jack took for the first 3 attempts
= 60 ÷ 3
= 20 s
New average time that Jack took for the 4 attempts
= 20 - 1.1
= 18.9 s
Total time that Jack took for the 4 attempts
= 4 x 18.9
= 75.6 s
Time that Jack should run in the 4
th attempt in order for him to make the improvement
= 75.6 - 60
= 15.6 s
Answer(s): 15.6 s