Question

In the Apple iPhone talk time distribution (mean = 7 hours, standard deviation = 0.8 hour), what percentage of iPhones have a talk time less than 6 hours?

a) 15.87%
b) 23.85%
c) 84.13%
d) 76.15%

Answer 1

To find the percentage of iPhones with a talk time less than 6 hours, we can use z-scores and the concept of standard deviation.

Step-by-step explanation:

To find the percentage of iPhones with a talk time less than 6 hours, we need to use the concept of standard deviation. In a normal distribution, we can use z-scores to calculate the percentage of data below a certain value. First, we need to calculate the z-score for the value 6 hours using the formula z = (x - mean) / standard deviation. z = (6 - 7) / 0.8 = -1.25 Using a z-table or a calculator, we can find that the percentage of data below -1.25 is approximately 10.61%. However, we are interested in the percentage of data below 6 hours, so we subtract this from 50% (which represents the percentage at the mean) to get 39.39%. Therefore, the correct answer is a) 15.87%.