SOLUTION: Recent research suggests that Americans make an average of 10 phone calls per day. Let the number of calls be normally distributed with a standard deviation of 3 calls. Compute t

Question 1180510: Recent research suggests that Americans make an average of 10 phone calls per
day. Let the number of calls be normally distributed with a standard deviation of 3 calls.
Compute the probability that an average American makes phone calls between 4 and 12
calls per day.
Answer by Boreal(15235) (Show Source): You can put this solution on YOUR website!
z=(x-mean)/sd
so the lower bound is (4-10)/3 or -2
and the upper bound is (12-10)/3 or +2/3
The probability for z between those two numbers is 0.7248
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