# Thread: need help solving this probability question.

1. ## need help solving this probability question.

Hey again guys.

The previous question i posted in the forum was already solved, but i have another question.

how do i solve:

What is the probability that a randomly selected ping pong ball will have a diameter between 2.28 and 2.30 inches?

Given: mean 2.3 inches and standard deviation of 0,04 inch.

Thanks.

2. What distribution does that question tell you to use?

If it's the normal distribution, then you need no skill to calculate a probability beyond what you already used to solve the question in your other thread.

3. Originally Posted by axz92
Hey again guys.

The previous question i posted in the forum was already solved, but i have another question.

how do i solve:

What is the probability that a randomly selected ping pong ball will have a diameter between 2.28 and 2.30 inches?

Given: mean 2.3 inches and standard deviation of 0,04 inch.

Thanks.
I assume diameter is a normal random variable.

Convert D1 = 2.28 and D2 = 2.30 into Z-values z1 and z2 using $\displaystyle \displaystyle Z = \frac{D - \mu}{\sigma}$. Then calculate Pr(z1 < Z < z2) in the usual way (you were shown this in your other thread http://www.mathhelpforum.com/math-he...ns-176862.html).

If you need more help, show all your working and say where you get stuck.