Think About It! Section
Select the answer you think is correct  then click the right arrow to proceed to the next question.
Customers at a gas station pay with a credit card, a debit card, or cash. Seventy percent don’t pay with cash, and 20% use a debit card. What is the probability that a randomly selected customer pays with cash?

The answer is 0.3. By the rule of the opposites since 70% don’t pay with cash, the other 30% do.

Correct. 0.3. By the rule of the opposites since 70% don’t pay with cash, the other 30% do.

The answer is 0.3. By the rule of the opposites since 70% don’t pay with cash, the other 30% do.

The answer is 0.3. By the rule of the opposites since 70% don’t pay with cash, the other 30% do.
Customers at a gas station pay with a credit card, a debit card, or cash. Seventy percent don’t pay with cash, and 20% use a debit card. What is the probability that a randomly selected customer pays with a credit card?

The answer is 0.5. Since all of the ways to pay are mutually exclusive we see that 30% pay with cash, 20% pay with a debit card so the remaining 50% must pay with a credit card.

The answer is 0.5. Since all of the ways to pay are mutually exclusive we see that 30% pay with cash, 20% pay with a debit card so the remaining 50% must pay with a credit card.

The answer is 0.5. Since all of the ways to pay are mutually exclusive we see that 30% pay with cash, 20% pay with a debit card so the remaining 50% must pay with a credit card.

Correct. 0.5. Since all of the ways to pay are mutually exclusive we see that 30% pay with cash, 20% pay with a debit card so the remaining 50% must pay with a credit card.
True or False: In tossing a fair coin, the probability that you get Heads on between 49% and 51% of the tosses decreases as the number of tosses increases.

The answer is FALSE. The Law of Large Numbers says that the probability increases for getting within 1% of what you expect as the number of trials goes up.

Correct. The Law of Large Numbers says that the probability increases for getting within 1% of what you expect as the number of trials goes up.
True or False: In spinning a roulette wheel, there is a 47% chance that the result comes up red. Thus, the chance that red comes up a majority of the time is greater with 50 spins than it is with 700 spins.

Correct. A majority means over 50% and getting more than 3% away from what you expect is more likely with fewer trials when things are more variable.

The answer is TRUE. A majority means over 50% and getting more than 3% away from what you expect is more likely with fewer trials when things are more variable.

Correct. It is unlikely that the method of payment for one customer affects the method used by another customer. However, if one customer is wearing a coat then it is more likely that the next customer is also wearing a coat (since it’s probably cold outside).

It is unlikely that the method of payment for one customer affects the method used by another customer. However, if one customer is wearing a coat then it is more likely that the next customer is also wearing a coat (since it’s probably cold outside).

Correct. $2.61. The expected value is found as the weighted average (summing amounts times probabilities).

The answer is $2.61. The expected value is found as the weighted average (summing amounts times probabilities).

The answer is $2.61. The expected value is found as the weighted average (summing amounts times probabilities).