The mean is μ = 60.0 and the standard deviation is σ = 4.0.
Find the probability that X is less than 53.0.

Question

The mean is μ = 60.0 and the standard deviation is σ = 4.0.
Find the probability that X is less than 53.0.

kropot72 · Answer

Are you expected to solve this by using a calculator or by using a standard Normal distribution table?

anonymous · Answer

Im not sure I was given the question and these answer choices 

        0.5589
	0.9599
	0.0401
	0.0802

kropot72 · Answer

Do you know how to find the z-score for X = 53?

anonymous · Answer

no, I've never understood anything standard deviation related

kropot72 · Answer

The z-score is found from
$$\large z=\frac{X-\mu}{\sigma}\ ............(1)$$
The first step in find the solution is to substitute the given values into (1) to find the z-score. Having found the z-score, a Standard Normal Distribution table is needed to find the the required cumulative probability that X < 53.

anonymous · Answer

okay so I found that the Z score is -1.750

kropot72 · Answer

You can use the value of z = -1.750 on the table here: http://www.math.bgu.ac.il/~ngur/Teaching/probability/normal.pdf

anonymous · Answer

thanks!

kropot72 · Answer

You're welcome :)