Find the 80th percentile of the distribution of the average of 49 fly balls.

Here we need to find 80th percentile for average of 49 fly balls

i.e. P(Z<z)=0.80

i.e. 0.5+P(0<Z<z)=0.80

P(0<Z<z)=0.8-0.8=0.3

Using standard normal table we get z=0.8415

Now z=xbar-mean/se=0.8415

So xbar=0.8415*7.14+250=256.00831

Hence 80th percentile is 256