Question

A game of chance involves spinning a wheel with 4 number on it. The wheel is designed so that the result of each spin Xhas the following probability distribution. 2 3 Result of a spin .x Probability : 0.50

(a) Find and interpret the mean of X.
(b) Find and interpret the standard deviation of x.
(c) It costs a player $5 for a single spin. The player will receive (in dollars) three times the number that appears. So the profit for one play of this game is Yeur 5. What is the mean and standard deviation of 7

Answer 1

Distribution table :

X : ___ 1 _____ 2 _____ 3 ______ 4

P(x) __0.50 __0.25 __ 0.15 ____ 0.10

Answer:

1.85 ; 1.014 ;` 0.55 ; 3.042

Explanation:

Probability distribution :

X : ___ 1 _____ 2 _____ 3 ______ 4

P(x) __0.50 __0.25 __ 0.15 ____ 0.10

The mean: E(x) = Σ(X * p(x))

(1*0.5) + (2*0.25) + (3*0.15) + (4 *0.10)

= 1.85

Standard deviation = sqrt(Var(x))

Var(x) = Σ(x²*p(x)) - E(x)²

Var(x) = ((1^2*0.5) + (2^2*0.25) + (3^2*0.15) + (4^2 *0.10)) - 1.85^2

= 4.45 - 3.4225

= 1.0275

Standard deviation = sqrt(1.0275)

Standard deviation = 1.0136567

Standard deviation(X) = 1.014

3.)

Cost of spin = $5

Amount, y to be received = 3 times the number that appears

y = 3x - cost of playing

y = 3x - 5

E(y) = E(3x - 5)

E(y) = E(3x) - 5

Recall :E(x) = 1.85

E(y) = 3(1.85) - 5

E(y) = 0.55

Standard deviation :Sd(y) =

Sd(3x - 5)

3(1.014)

= 3.042