expected value of x and deviation value of x (HELP!)

Question

x   probability  product xp

1    .20

4    .15

7    .40

10   .25

 

I need to find the expected value of x as well as the deviation value of x.

i got 6.1

3.49939

Answer 1

I got 6.1 and 3.46.  The difference in standard deviation could be rounding differences.  I rounded nothing (except final answer), and when I try to round some of the intermediate numbers, I get closer to 3.44, not higher like your answer.  I don't know what your instructor expects in terms of rounding, but your answer is close but not quite there.  You might want to recheck all the calculations and see if you still get 3.49939.  Otherwise you might want to post the work you did to get that.

 

(EDIT:  It's always possible there's another method to get this that I'm not aware of.)