Question

a batsman has certain average runs for 20 innings. in the 21st inning, he served 107 runs thereby increasing his average by 2. what is his average after 21 innings ?

Answer 1

average is equal to total runs / total innings
average into 20 is equal to total runs (eqn1)

new average is equal to total runs scored + 107 / 21
21 * (average +2)=total runs scored + 107
21*average +42=20*average +107
Average =65

Answer 2

Concept

Average is the sum of observation divided by number of observations.

The formula for calculating average is:

Average=sum of numbers / number

Given

In the 21st innings he served 107 runs.

To find

Batsman's average after 21st innings if the average increased after 21st innings is 2.

Explanation

let the average of Batsman after 20 innings be x.

average=sum/20

x=sum/20

sum=20x.

Sum after 21st innings=20x+107

Average after 21st innings=x+2

average=sum/numbers

x+2=(20x+107)/21

21(x+2)=20x+107

21x+42=20x+107

21x-20x=107-42

x=65

Hence if Batsman served 107 runs in 21st innings and his average increased by 2 so after 21st innings the average will be 65+2=67.

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