A set of data with a mean of 45 and a standard deviation of 8.3 is normally distributed. Find the value that is –2 standard deviations away from the mean.

a.61.6
b.28.4
c.43.0
d.20.1

Question

A set of data with a mean of 45 and a standard deviation of 8.3 is normally distributed. Find the value that is –2 standard deviations away from the mean.
 	
	a.61.6
	b.28.4
	c.43.0
	d.20.1

amistre64 · Answer

the formula to find z is:$$z=\frac{x-mean}{sd}$$
solving for x we get:$$mean+z(sd)=x$$
they give you the mean, sd, and z values to play with

amistre64 · Answer

or if we simply reason it out:

-2 standard deviation; when 1 standard deviation is equal to 8.3 is

45 - 8.3 - 8.3

anonymous · Answer

28.4

amistre64 · Answer

correct