# Ajit has a certain average for 9 innings. In the tenth innings, he scores 100 runs thereby increasing his average by 8 runs. His new average is:

A. 20

B. 21

C. 28

D. 32

### Solution(By Examveda Team)

Let Ajit's average be x for 9 innings. So, Ajit scored 9x run in 9 innings.
In the 10th inning, he scored 100 runs then average became (x+8). And he scored (x + 8) × 10 runs in 10 innings.
Now,
\eqalign{ & \Rightarrow 9x + 100 = 10 \times \left( {x + 8} \right) \cr & {\text{or}},\,9x + 100 = 10x + 80 \cr & {\text{or}},\,x = 100 - 80 \cr & {\text{or}},\,x = 20 \cr & {\text{New}}\,{\text{average}} = \left( {x + 8} \right) \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 28\,{\text{runs}} \cr}

1. Ok, Good.., But when student doing competitive exams we they short cut method, plz explain in short cut methods

2. It's the so best learning website to improve mathematical calculation

3. 100-(8*9)=28

4. Good

5. Let, initial average = x
Acq,
10(x+8)-9x = 100
x = 100-80 = 20
New average = 20+8 = 28

6. thanks

7. thanks

8. Good and clear explanation

9. Good Solutions

10. Didn't get it.

11. Let Ajit's average be x for 9 innings. So, Ajit scored 9x run in 9 innings.
In the 10th inning, he scored 100 runs then average became (x+8). And he scored (x+8)*10 runs in 10 innings.
(9x+100)/10 = x+8 (since in 10th inning, 100 more then 9th inning and average gets increses by 8)
therefore on solving this equation we get ,
x=20
But the new average is increased by 8 runs
therefore x+8 i.e 20+8 = 28..

12. Nice solution

13. Can't understand

14. c

15. 28

16. Best questions

17. c

18. Its 28

19. 28

Related Questions on Average