I'm not sure this is the right area buuut...

[victoria91]

Can anyone help me solve this?

In a set of 100 ACT scores that are normally distributed and with a mean of 23 and standard deviation of 4.69,


a. How many scores are expected to be lower than 18.31 (one standard deviation below the mean)?


b. How many of the 100 scores are expected to be below 32.38 (two standard deviations above the mean)?


I don't even know where to start. It's for my schoolwork. Thanks in advance.

 

[Deleted member 4993]

Can anyone help me solve this?

In a set of 100 ACT scores that are normally distributed and with a mean of 23 and standard deviation of 4.69,


a. How many scores are expected to be lower than 18.31 (one standard deviation below the mean)?


b. How many of the 100 scores are expected to be below 32.38 (two standard deviations above the mean)?


I don't even know where to start. It's for my schoolwork. Thanks in advance.

Have you studied:

Standard Normal distribution (Z-distribution)?

 

[Steven G]

Look it up in your z-table

 

[Dr.Peterson]

Can anyone help me solve this?

In a set of 100 ACT scores that are normally distributed and with a mean of 23 and standard deviation of 4.69,


a. How many scores are expected to be lower than 18.31 (one standard deviation below the mean)?


b. How many of the 100 scores are expected to be below 32.38 (two standard deviations above the mean)?


I don't even know where to start. It's for my schoolwork. Thanks in advance.

It's possible that you haven't yet learned about the "z-score", but have seen a graph of the normal distribution like this:

68–95–99.7 rule - Wikipedia

en.wikipedia.org

Whatever you have learned about the normal distribution, please tell us, so we can use what you know to help. If you followed our guidelines, you would have an answer by now:

Posting Guidelines (Summary)

Welcome to our tutoring boards! :) This page summarizes the main points from our posting guidelines. As our name implies, we provide math help (primarily to students with homework). We do not generally post immediate answers or step-by-step solutions. We don't do your homework. We prefer to...

www.freemathhelp.com

 

[HallsofIvy]

Can anyone help me solve this?

In a set of 100 ACT scores that are normally distributed and with a mean of 23 and standard deviation of 4.69,[/QU


a. How many scores are expected to be lower than 18.31 (one standard deviation below the mean)?


b. How many of the 100 scores are expected to be below 32.38 (two standard deviations above the mean)?


I don't even know where to start. It's for my schoolwork. Thanks in advance.

Oh, dear! If this is schoolwork and you "don't even know where to start" have you missed classes? For a value of x, you need to use the "standard normal variable" z= (x- 23)/4.69.

To find the percentage lower than 18.31 use z= (18.31- 23)/4.69= -4.69/4.69= -1 (so one standard deviation below the mean as you were told.) Look the probability in a table of the standard normal distribution (there is one here: https://www.bing.com/images/search?...ndex=0&idpp=overlayview&ajaxhist=0&ajaxserp=0) or use whatever app you have to do that.

 

[victoria91]

So, I was homeschooled and no, we didn't go over this. I'm now in online college and this term is Math, this is for my discussion post & no, we haven't gone over this either.

Thank's for the replies.

 

[Deleted member 4993]

So, I was homeschooled and no, we didn't go over this. I'm now in online college and this term is Math, this is for my discussion post & no, we haven't gone over this either.

Thank's for the replies.

read the referenced web-site in response #4.

Please ask us if you do not understand it.