A department store has determined that 65% of all their sales are credit sales. A random sample of 90 sales is collected. What is the standard deviation assuming the distribution is normal?

Define the term standard deviation?

In a bell-shaped distribution, 95 % of the data falls within 1 standard deviation of the mean.

According to the U.S. Bureau of Labor Statistics, all workers in America who had a bachelor's degree and were employed earned an average of $1152 a week in 2010. A recent sample of 676 American workers who have a bachelor's degree showed that they earn an average of $1171 per week. Assume that the population standard deviation is $165. Test the claim that the current mean weekly earnings of American workers with a bachelor's degree is greater than $1152. Show all the steps of a hypothesis test.