21-25. A survey of 10 tablet computers reveal that their prices are normally distributed with a mean of $171 and a standard deviation of $73.

21. We want to know the probability of finding a table that costs more than $390. As a first step, we calculate the z score for $390. What is that z score? Note: It is a one digit number without any decimals. For example: 9.

Hint: We get the z score by using the z score formula: (specific score-mean)/standard deviation. The specific score is $390, the mean is $171, and the standard deviation is $73.