Question 1162116
z=(x-mean)/sd 
=(80-80)/7=0
=(90-80)/7=1.43
want z between 0 and 1.43, which is 0.4236
OR, and you can do this with all, go to 2nd VARS 2 Normalcdf (80,90,80,7). put in the two limits followed by the mean and the sd. ENTER. 

so for 4. put in for normalcdf (85,96,80,7)ENTER  0.2264 probability.

for 6, put in a large number like 1000. normal cdf (93,1000,80,7)

for 9. use 2ndENTER 2 invnorm (0.30,80,7) ENTER. Get 76.3
z(0.30)=-0.5244
z=(x-mean)/sd
-0.524*7=x-mean
x=80-3.67=76.3

there is 21.12% remaining, (100-78.88) and half of that is 10.56%
inv norm (0.1056,50,7)=41.25
that is 8.75 below the mean. The normal function is symmetrical, so the other side will be 8.75 above the mean, and that would be 58.75.

Check with normal cdf (41.25, 58.75, 50, 7)=0.7887, which is off by rounding error. Use 3 decimal places.