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Introduction to Probability and Statistics: Practice Questions with Answers

Curriculum: Introduction To Probability And StatisticsGrades: 6–8Questions: 12Mode: Practice

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1. A weather forecaster says there is a probability of 0 that it will snow today. What does this mean?

  1. It snowed yesterday
  2. It is impossible for it to snow today
  3. It is certain to snow today
  4. It might snow, but only a little
Show the answer
Answer: B. It is impossible for it to snow today
A probability of 0 means the event cannot happen at all, so it is impossible.

2. You flip a fair coin. What is the probability of getting heads?

  1. 1
  2. 1/4
  3. 1/2
  4. 1/3
Show the answer
Answer: C. 1/2
A coin has 2 equally likely outcomes (heads or tails), and 1 of them is heads, so the probability is 1/2.

3. A bag has 4 red marbles and 4 blue marbles. What is the probability of picking a red marble?

  1. 1/2
  2. 4/4
  3. 3/4
  4. 1/8
Show the answer
Answer: A. 1/2
There are 4 red marbles out of 8 total marbles, so the probability is 4/8, which simplifies to 1/2.

4. What is the mode of this data set: 3, 5, 5, 7, 8, 5, 9?

  1. 9
  2. 5
  3. 3
  4. 7
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Answer: B. 5
The mode is the value that appears most often in a data set. Here, 5 appears three times, more than any other number.

5. What is the median of this data set: 2, 4, 6, 8, 10?

  1. 2
  2. 10
  3. 4
  4. 6
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Answer: D. 6
When data is listed in order, the median is the middle value. In 2, 4, 6, 8, 10, the middle number is 6.

6. A spinner is divided into 6 equal sections numbered 1 through 6. What is the probability of landing on a number greater than 4?

  1. 4/6
  2. 1/6
  3. 3/6
  4. 2/6
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Answer: D. 2/6
The numbers greater than 4 are 5 and 6, which is 2 favorable outcomes out of 6 total sections, giving 2/6.

7. Rolling a standard six-sided die, what is the probability of rolling a 7?

  1. 1/6
  2. 1
  3. 1/2
  4. 0
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Answer: D. 0
A standard die only has the numbers 1 through 6, so rolling a 7 is impossible, which means the probability is 0.

8. What is the range of this data set: 12, 18, 9, 22, 15?

  1. 12
  2. 9
  3. 22
  4. 13
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Answer: D. 13
The range is found by subtracting the smallest value from the largest value: 22 minus 9 equals 13.

9. A jar contains only yellow candies. What is the probability of picking a yellow candy?

  1. 3/4
  2. 1/2
  3. 1
  4. 0
Show the answer
Answer: C. 1
Since every candy in the jar is yellow, picking a yellow candy is certain, so the probability is 1.

10. Which of these values could NOT be a probability?

  1. 0
  2. 0.5
  3. 1.5
  4. 1
Show the answer
Answer: C. 1.5
Probabilities must be between 0 and 1, so 1.5 is not a valid probability since it is greater than 1.

11. In a class, 10 students prefer pizza and 15 prefer tacos. If a student is picked at random, what is the probability they prefer pizza?

  1. 10/25
  2. 15/25
  3. 10/15
  4. 25/25
Show the answer
Answer: A. 10/25
There are 10 pizza-preferring students out of 25 total students (10 + 15), so the probability is 10/25.

12. What is the mean of this data set: 4, 6, 8, 10?

  1. 6
  2. 9
  3. 8
  4. 7
Show the answer
Answer: D. 7
The mean is found by adding all values (4 + 6 + 8 + 10 = 28) and dividing by the number of values (4), giving 28 / 4 = 7.
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