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
