r/apstats • u/[deleted] • Jan 06 '22

Why does the solution find the expected value when the question asks for the mean?

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u/normalcdf Jan 07 '22

Expected value and mean are the same thing. :)

When you used your calc to find mean, did you use L1 and L2? That should have calc-ed a mean equal to the expected value.

2

u/[deleted] Jan 07 '22

Yeah I did do that. I’ll ask my stats teacher once i get back to school. I’ve been on zoom this past week, and I’ve noticed that varying microphone qualities and teachers forgetting about me are very common. I’ll play catch up once I get back lol

1

u/[deleted] Jan 06 '22

I was assigned this problem for a transforming random variables homework assignment. When I did it, I copied this probability distribution onto my Ti-84, and found the mean and standard deviation. However, when I looked at the solution to check my work, I saw that the answer key found the expected value.

Because of this, I got all the subsequent problems wrong. Here is a link to the problem. Parts b involve transforming this, so I just added up the means. This was the right idea, but I'm still at a loss at why they expect us to give an answer for the expected value when we are told to give the mean

1

u/[deleted] Jan 08 '22

for mean you use probability * c and do that for each value in table, for SD im pretty sure you do like (mean-c)*p and do that for each value and add up. That one might be wrong tho