Answer:
Approximately 68% of daily phone calls will be in this interval.
Step-by-step explanation:
The Empirical Rule states that, for a normally distributed random variable:
68% of the measures are within 1 standard deviation of the mean.
95% of the measures are within 2 standard deviation of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean = 57
Standard deviation = 7
What is the approximate percentage of daily phone calls numbering between 50 and 64
50 = 57 - 7
So 50 is one standard deviation below the mean
64 = 57 + 7
So 64 is one standard deviation above the mean
By the Empirical Rule, approximately 68% of daily phone calls will be in this interval.
