6.18 Empirical rule Verify the empirical rule by using Table A, software, or a calculator to show that for a normal distribution, the probability (rounded to two decimal places) within

a. 1 standard deviation of the mean equals 0.68.

b. 2 standard deviations of the mean equals 0.95.

c. 3 standard deviations of the mean is very close to 1.00.

In each case, sketch a normal distribution, identifying on the sketch the probabilities you used to show the result.