Statistics word problem

Question

In a survey amongst freshmen at StudyMore College, the average number of hours spent studying for their math class was 15.4 hours per week with a standard deviation of 2.65. Assuming the population is normally distributed, what is the proportion of the population who study less than 12 hours per week?

Answer 1

We will need the z-score formula.  We are given the following:  µ = 15.4, X = 12, and σ = 2.65.

 

z = X - μ/σ  =  12 - 15.4 / 2.65 = -3.4/2.65 = -1.28

 

P(Z < -1.28) = 0.1003

 

The proportion of the population who study less than 12 hours is 0.1003.

 

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