Question

Pranalee was practising for a 100 m running race. She ran 100 m distance 20 times. The time required, in seconds, for each attempt was as follows.
18 , 17 , 17 , 16 , 15 , 16 , 15 , 14 , 16 , 15 , 15 , 17 , 15 , 16 , 15 , 17 , 16 , 15 , 14 , 15
Find the mean of the times taken for running.

Answer 1

Hi ,


Sum of the time required to finish the race

= 18 + 17 + 17 + 16 + 15 + 16 + 15 + 14 + 16 + 15 +

+ 15 + 17 + 15 + 16 + 15 + 17 +16 + 15 + 14 + 15

= 314---( 1 )

Number of observations = 20 ----( 2 )

Mean = ( 1 )/( 2 )

= 314/20

= 15.7

Therefore ,

Mean of the times taken for running = 15.7

I hope this helps you.

: )

Answer 2

Hi ,

➡️Answer: 15.7 sec

➡️Solution:

To calculate mean add all the seconds of 20 attempts of running.
Divide by total attempts.

A.T.Q. time in seconds for all 20 times are as follows

18 , 17 , 17 , 16 , 15 , 16 , 15 , 14 , 16 , 15 , 15 , 17 , 15 , 16 , 15 , 17 , 16 , 15 , 14 , 15

So, add all these terms
=
$= 18 + 17 + 17 + 16 + 15 + 16 \\ + 15 + 14 + 16 + 15 + \\ 15 + 17 + 15 + 16 + 15 + 17 + \\ 16 + 15 + 14 + 15 \\ = 16 \times 5 + 14 \times 2 + 17 \times 4 + \\ 15 \times 8 + 18 \\ \\ = 80 + 28 + 68 + 120 + 18 \\ \\ = 314$
Mean time =
$\frac{314}{20} \\ \\ = 15.7 \: \: sec$
hope it helps you