The table shows the time taken by Mark to run 100 metres during his training sessions. After 3 attempts, Mark wanted to improve his average time taken by 0.4 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) |
25 |
24 |
20 |
? |
Total time that Mark took for the first 3 attempts
= 25 + 24 + 20
= 69 s
Average time that Mark took for the first 3 attempts
= 69 ÷ 3
= 23 s
New average time that Mark took for the 4 attempts
= 23 - 0.4
= 22.6 s
Total time that Mark took for the 4 attempts
= 4 x 22.6
= 90.4 s
Time that Mark should run in the 4
th attempt in order for him to make the improvement
= 90.4 - 69
= 21.4 s
Answer(s): 21.4 s