Hello :D

I need some help with my statistics homework assignment. The question is... The number of suits sold per day at a retail store is shown in the table, with the corresponding probabilities

Number if suits sold, X 19 20 21 22 23
Probability, P(X) 0.2 0.2 0.3 0.2 0.1


Could someone please teach me how to find the mean, variance, and standard deviation of this data?

Thank you

Yes, it's easy. This is a "discrete non-binomial distribution".




x P(x)
-------------------
19 .2
20 .2
21 .3
22 .2
23 .1




For the mean:

{\mu}=\sum xP(x)

That is, multiply the x by its P and add them up.

Variance:

{\sigma}^{2}=\sum (x-\mu)^{2}P(x)

Once you have your mean, subtract it from each x, square it, multiply by its probability. Add them all up.

standard deviation:

\sqrt{{\sigma}^{2}}

Let me know what you get and we can check it.