The number of customers at your company's store on a given day has a bell-shaped normal distribution with a mean of 60 and a standard deviation of 10. What percentage of days do you expect to have between 50 and 70 customers?
Since one standard deviation = 10
Then the given range of 50-70 falls within 1 standard deviation on either side of the mean
Approxinatelt 34.13% of the measurements fall within one standard deviation on either side of the mean
So 2 [34.13% ] = 64.26% of the days have between 50 and 70 customers