number puzzle

[alison6399]

In a cricket match the average number of runs for the first 20 overs was 2.

After a further 20 overs the average rose to 7.

What was the average of runs scored in the last 20 overas only?

Pse show all workings. Thanx

[barterboy]

first 20 overs = 40 runs
after 40 overs av= 7 therefore 280 runs after 40 overs
therefore 240 runs in the second 20 overs therefore 12 runs averaqge= 12

[bridgenut]

to average 7 runs an over the score has to be 40*7=280 runs
40 runs have been scored in the first 20 overs which means 240 runs have been scored in the last 20 overs . So 240/20 =12 runs an over
20*2=40
20*12=240
total 40 overs
total 280 runs