Basic Probability

Test your knowledge of probability.

Probability is probably (no pun intended) one of the least intuitive branches of mathematics, yet probabilistic reasoning is very important. How well do you understand probability?

Question Title

* 1. You roll a 6-sided die three times. What is the probability that you get a 6 on all three rolls?

1 in 6

1 in 12

1 in 18

1 in 24

1 in 36

1 in 100

1 in 200

1 in 216

1 in 222

1 in 256

1 in 336

1 in 400

1 in 600

1 in 1200

1 in 3600

None of the above.

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* 2. You flip a fair coin nine times and get heads all nine times. What is the probability that the next flip will be heads?

1 in 2

1 in 10

1 in 100

1 in 1000

1 in 1024

1 in 10,000

It is impossible to get 10 heads in a row.

10% chance of another heads.

Heads is hot, so it must be 100%

None of the above.

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* 3. The Greens have two children. What is the probability that both are girls?

10%

15%

20%

25%

30%

33%

35%

50%

67%

75%

90%

99%

100%

None of the above.

Not enough information.

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* 4. If the Browns have two children, what is the probability that at least one is a girl?

10%

15%

20%

25%

30%

33%

35%

50%

67%

75%

90%

99%

100%

None of the above.

Not enough information.

Question Title

* 5. The Grays have two children, the oldest being a girl. What is the probability that both children are girls?

10%

15%

20%

25%

30%

33%

35%

50%

67%

75%

90%

99%

100%

None of the above.

Not enough information.

Question Title

* 6. If the probability of being nearsighted given that you are left-handed is 20%, then the probability that you are left-handed given that you are nearsighted is also 20%.

True

False

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* 7. Independence means that the outcome of the next trial is not influenced by the outcomes of previous trials.

True

False

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* 8. You see a person reading The New York Times on the subway. Which of the following is more likely?

The person has a PhD.

The person has only a high school education.

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* 9. You’re in a game show and there are three doors, one has a car behind it, the other two have goats. You would rather have a car than a goat. When you pick one of the doors, the host opens one of the other doors to show that it has a goat behind it. To have a higher chance of winning the car, you should you change your guess to the other unopened door.

True

False