# Math Help - Probability Help

If the hourly sales at a certain register in a supermarket are normally distributed with a mean of $650 and a standard deviation of$60, find the probability that the sales during a randomly selected hour are greater than $800. 2. ## Re: Probability Help Originally Posted by khalyar If the hourly sales at a certain register in a supermarket are normally distributed with a mean of \$650 and a standard deviation of \$60, find the probability that the sales during a randomly selected hour are greater than \$800.
Find your z-score and look it up in the table.

z-score = $\dfrac{800-650}{60}$

Note you want the probability that sales are greater than \$800 so you take 1 - Pr[sales < \$800] = 1 - (probability corresponding to the above z-score)