Finding Expected Values of Random Variables

A car dealer buys hybrids for $21,000 each and sells them for $24,500 each. Find his expected weekly profit.

• $2,380

• $5,355

• $8,109

• $37,485

HINT: Read carefully! And think about the TOTAL amount of money being gained or lost in each situation!

• $275

• $625

• $2,750

• $6,250

Given the probability model in the table below, what is the expected value of the random variable?
  X        50          20        5
P(X)     0.1         0.3      0.6

• 14

• 4.67

• 5

• 7.5

A small store keeps track of the number X of customers that make a purchase during the first hour that the store is open each day. Based on the records, X has the following probability distribution. What is the average number of customers that the owner can expect to make a purchase in the first hour of opening?

• 0.2

• 1.4

• 2.0

• 3.0

If the expected value is negative, are you expected to win?

• yes

• no

A game consists of rolling a colored die with three red sides, two green sides, and one blue side. A roll of a red loses. A roll of green pays $2.00. A roll of blue pays $5.00.   The charge to play the game is $2.00. What is the expected value

• $0

• -$0.50

• $.67

• $-1.50

Find the value of k

• ¹/₁₅

• ¹/₅

• ¹/₁₀

• ¹/₁₄

Find the value of k

• ¹/₁₅

• ¹/₁₆

• ¹/₁₇

• ¹/₁₄

Find the value of q

• 0.85

• 0.15

• 0.25

• 0.05

Find the value of p

• 0.9

• 0.1

• 0.3

• 0.15