Question

400 draws are made at random with replacement from 5 tickets that are marked -2, -1, 0, 1, and 2 respectively. Find the expected value of
a) the number of times positive numbers appear
b) the sum of all the numbers drawn
c) the sum of the positive numbers drawn

Answer 1

we dealt with this problem earlier today, what is it from?

Answer 2

answer please??

Answer 3

so you don't want me to teach you to do it?

Answer 4

if u can please do so

Answer 5

so with a sample this big, you can assume you get each of the cards exactly 1/5 of the time

Answer 6

ya

Answer 7

1 and 2 are positive. zero is not positive nor negative.

Answer 8

i know these.. can u quickly tell me the main steps in solving this??

Answer 9

1) find out how many positive numbers are picked assuming that each number is picked exactly 1/5 of the time
2) have the insight that the sum of all five numbers is zero
3) add and multiply to find the sum of all the positive numbers picked

Answer 10

for the first question i got the answer as 160... but how to do the second and third??

Answer 11

obviously second answer is zero... but third??

Answer 12

third: you know how much 1 was drawn and you know how much 2 was drawn

Answer 13

can u please explain with the solution??

Answer 14

let x be the number of times each number is drawn
the sum of the positive numbers is 1x + 2x
do you see why?

Answer 15

ya can get it

Answer 16

so the answer must be 80+160 right??

Answer 17

yes

Answer 18

thank you

Answer 19

thank you for learning