Question

The probability to win a prize is 0.25 with one go. The game is played for 10 times. X denotes the number of prices won. Find E(X)

Answer 1

No calculator allowed.

Answer 2

If I understand the problem correctly then, your x values will be {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, and your p values will be?

Answer 3

E(X) = np = 10(.25) = 2.5

This is a binomial distribution right?

Answer 4

he plays the game 10 times - why the 0? or is 0, 1, 2... the number of prizes that he can possibly win?

Answer 5

Yes, x represents the values of each outcome.

Answer 6

oh and yea E(X) = np = mean = 2.5

Answer 7

p(x) should be the probability of any particular outcome.

Answer 8

we get to our second point. P(X<2) (X is less than or equal to two)

Answer 9

expression for that probability is enough for answer no need to calculate it

Answer 10

i liked at standardized variable list and it said 0.9773 for 2

Answer 11

*looked at

Answer 12

@Jire ...the second point:

P ( X ≤ 2) ≈ 0.526

difficult to type full solution, not sure how to properly use equation box.

Answer 13

you can just tell me how to basically get there

Answer 14

It's just P(X=0) + P(X=1) + P(X=2)

Answer 15

oh okay so using this formula gives me the - probability of that with 10 tries of 0.25 probability of getting the prize, less than or equal to two prizes are won??

Answer 16

Well if it's P(X<2), then it's just P(X=0) + P(X=1)

Answer 17

Yeah, you're interpreting it right.

Answer 18

thx