Question

How many standard deviations are there in a normal distribution curve?

A. 1 above and and below

B. 2 above and below

C. 3 above and below

D. 4 above and below

Answer 1

Solution : In normal distiribution curve use three standard deviations.

In Normal disrtribution curve use emperical rule.

For an approximately normal data set, the values within one standard deviation of the mean about the 68% data, the values within two standard deviation of the mean about the 95% data, the values within threestandard deviation of the mean about the 99.7% data.

Empirical rule also called three-sigma rule of thumb.

With the referrence of empirical rule we use 3 standard deviation in the Normal distribution curve.

So we choose option C. 3 above and below.