11 Plus Exams Forum

Hi
Can anyone help answer this maths question from bond books. A cricketer's average score for 6 innings is 12 runs. What must he score in his next innings to make his average 13.

Answer is 19 but I just don't get it.

Please help!!!!!

If his average score over 7 runs was going to stay at 12 - he would need to score 12 (obviously)

To bump the average up to 13 he would have to score an 'extra' for every run completed ie. 7 - so he would have to score an extra 7 runs.

12 + 7 = 19

Hope this helps.

avg across 6 innings is 12

need to get avg across 7 of 13

to continue with same avg (12) he would need to score 12 in next innings.
to raise the avg for all 7 to be 13 he needs to score an additional run for each of the 7 innings so in total he needs to score 12 + 7 i.e. 19

toolate wrote:If his average score over 7 runs was going to stay at 12 - he would need to score 12 (obviously)

To bump the average up to 13 he would have to score an 'extra' for every run completed ie. 7 - so he would have to score an extra 7 runs.

12 + 7 = 19

Hope this helps.

still not with it

slush wrote:

toolate wrote:If his average score over 7 runs was going to stay at 12 - he would need to score 12 (obviously)

To bump the average up to 13 he would have to score an 'extra' for every run completed ie. 7 - so he would have to score an extra 7 runs.

12 + 7 = 19

Hope this helps.

still not with it

thanks just worked it out. Fab forum

For each of the previous 6 innings he has scored 12 runs. If his average for those had been thirteen runs he would have had to have scored an extra run each time - 6 in total. He needs to make up these 6 on his next innings as well as get the new average of 13 runs. 6+13=19

If it's still not clear, try drawing a table with innings going down the left hand side and two separate columns for old average and new average. Remember that the old average will go down 6 innings and that your new average must work across 7.

Total runs after 6 innings = 12 (average score after 6 innings) x 6 = 72

Total runs after 7 innings = 13 (average score after 7 innings) x 7 = 91

Hence run needed in the 7 inning to get an average of 13 runs) = 91-72 = 19

dez wrote:Total runs after 6 innings = 12 (average score after 6 innings) x 6 = 72

Total runs after 7 innings = 13 (average score after 7 innings) x 7 = 91

Hence run needed in the 7 inning to get an average of 13 runs) = 91-72 = 19

thanks i get it now