Respuesta :

21.19%

First you need to find the z-score with

X- Mean
-----------       =  Zscore
Standard
Deviation

Then use your z table (should be on your formula sheet if not look one up) 
to find your proportion (in this problem it would be .2119)  and convert it to a percent.

So plug everything in 

6.64-7.2
------------ = Z-Score
     .7

Z-Score= 0.8

The table showed our proportion to be .2119

therefore your percent is 21.19%