frequency distribution

[studybrat]

I'm not sure if I'm doing this right; I need to build up my math confidence, I think.

Anyway, here it is:

Use the frequency distribution below to answer the following questions about the nubmer of interviews for recent college graduates (X).

X: f:
0 10
1 10
2 10
3 30
4 50
5 60
6 30

What is the mean? I mult. X(f), then added up the products to get 800
I then add up the column of f to get 200. Finally I divided 800 by 200 to get a mean of 4. Hopefully I did this correctly.

Then it asks: What is the frequency for four interviews, seems simple enough, I put 4*50 = 200. Is this what is meant?

For the next 3 parts, I need some extreme help.

What proportion of the recent graduates had 5 or fewer interviews?
Hmm, does this have to do with z scores? Is this how you do it:
5-4/by standard deviation = z score, then subtract that from .5000 ???

Also, what is the probability of having 4 or 5 interviews?

And then last, what is the probability of getting an interview?

 

[tkhunny]

It may be easier to work from this version:

X: f: %
0 10 10/200 = 0.05
1 10 10/200 = 0.05
2 10 10/200 = 0.05
3 30 30/200 = 0.15
4 50 50/200 = 0.25
5 60 60/200 = 0.30
6 30 30/200 = 0.15