A. That's correct

B. It's a linear formula in the form of c = am + b

a = 0.01 and b = 0.15

Therefore

c = 0.01m + 0.15

C. 0.29 = 0.01m +0.15

0.14 = 0.01m

14 = m

The phonecalls cost the same amount at 14 minutes.

D.

Which is the area under normal curve from 0.25 to - the area from 0.25 to 0.29

0.29 in standard units: (0.29 - 0.25) / 0.3 =

Which yields from the standard distrbution table: 0.5 - 0.4082 = 0.0918, which gives 9.18%