Question

The Coaches of the NJ Pride Women’s Soccer Club surveyed 144 of their players to see how much time they spend practicing on their own during the weekends. The study showed that the players practice an average of 20 hours on their own with a standard deviation of 9 hours.

(a) What is the standard error of the mean?

(b) Compute the probability the sample mean is greater than 20 hours?

(c) Compute the probability the sample mean is less than 18 hours?

(d) Compute the probability the sample mean is between 18 and 21 hours?

Answer 1

a) As n=144>30, as per central limit theorem distribution of sample mean is also normal with standard error as

SE=

b)Here we need to find

As sample mean is normally distributed we can convert sample mean to z

c)Here we need to find

As sample mean is normally distributed we can convert sample mean to z

d)Here we need to find

As sample mean is normally distributed we can convert sample mean to z

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