I need to find one, two and three standards deviations above the mean over 14.88 and one,two and three below this mean

Question

I need to find one, two and three standards deviations above the mean over 14.88 and one,two and three below this mean. The standard deviation in this equation is 2.8

Answer 1

Since you know the standard deviation and the mean, you simply add or subtract the standard deviation to/from the mean.

 

1st standard deviation above = mean + standard deviation = 14.88 + 2.8 = 17.68

2nd standard devation above = mean + 2standard deviation = 14.88 + 2.8 + 2.8 = 20.48

3rd standard devation above = mean + 3standard deviation = 14.88 + 2.8 +2.8 +3.8 = 24.28

 

1st standard deviation below = mean - standard deviation = 14.88 - 2.8 = 12.08

2nd standard deviation below = mean - 2standard deviation = 14.88 - 2.8 - 2.8 = 9.28

3rd standard deviation below = mean - 3standard deviation = 14.88-2.8-2.8-2.8 = 6.48

 

 

Answer 2

Hi Anthony,

            I'll show you how to find one above and one below.You should be able to  do the rest.

 

Let z=μ +- nσ where μ is the mean and σ is the standard deviation and n is the multiple above or below.

 

so lets calculate two standard deviations above the mean z=14.88 + 2x2.8 = 20.48 next lets do three below Z=14.88-3x2.88 = 6.24.

 

Hope this helps

 

Jim