Question 658744
Draw a bell curve with the mean (middle of the bell) at 60. 

The standard deviation is 5, so 55 is one standard deviation below the mean and 65 is one standard deviation above the mean. Look in your book and you will see that the percentage of observations within one standard deviation is 68%.

The standard deviation is 5, so 50 is two standard deviation below the mean and 70 is two standard deviation above the mean. Look in your book and you will see that the percentage of observations within two standard deviation is 95%.

The standard deviation is 5, so 45 is three standard deviation below the mean and 75 is three standard deviation above the mean. Look in your book and you will see that the percentage of observations within three standard deviation is 99%.