A baseball player has a batting average of 0.315. Estimate how many hits he will get in his next 43 at bats.
A batting average of 0.315 means 315 hits out of 1000 at-bats or 315/1000=63/200 which means 63 hits out of 200 at-bats or 34 hits out of 108 at-bats which equals 34/108=0.3148 which rounds to 0.315.
You can set up a proportion: 315/1000=x/43 where x=# of hits.
Cross multiply to get 315*43=1000*x
He will get about 13-14 hits in his next 43 at bats-13/43=0.302 and 14/43=0.325
The simplest way to solve the problem is to multiply 0.315*43=13.545 or about 13-14 hits
Look at it this way; if he is batting 0.300 that means he gets 3 hits in every 10 at-bats. In 43 at-bats there are
4 tens so he should get at least 3*4=12 hits !