A cricketer has a certain average score for 9 innings. In the tenth innings he scores 100 runs, thereby increasing his average by 8 runs. What is his new average?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 28 runs
The total runs equal the average multiplied by the number of innings. The total after 10 innings is the old total plus the 100 runs of the tenth innings.
Let the average for 9 innings be \(a\); total runs \(=9a\)
After the tenth innings the average is \(a+8\); total runs \(=10(a+8)\)
\(9a+100=10a+80\)
\(a=100-80=20\)
New average \(=a+8=20+8=28\) runs
The new average is 28 runs. (20 runs is the old average, Option (4).)