AD
« Back

STEPCAI

« All free sample lessons

Statistics and Probability: Practice Questions with Answers

Curriculum: Statistics and ProbabilityGrades: 10–12Questions: 12Mode: Practice

These are the real questions from this STEPCAI practice lesson. Read each question, pick your answer, then open Show the answer to check yourself and read why it is right. On STEPCAI the same lesson runs interactively: you click an answer and get instant feedback, and a free account keeps your scores.

Practice this lesson free with instant feedback

Free. New visitors accept the Software License Agreement first.

1. What is the mean of the data set 4, 8, 6, 5, 3?

  1. 6.5
  2. 4.3
  3. 5.0
  4. 5.2
Show the answer
Answer: D. 5.2
The mean is found by adding all the values (4+8+6+5+3=26) and dividing by the number of values (5), giving 26/5 = 5.2.

2. What is the median of the data set 7, 2, 9, 4, 5?

  1. 9
  2. 4
  3. 7
  4. 5
Show the answer
Answer: D. 5
The median is the middle value when the data is arranged in order. Sorting the set gives 2, 4, 5, 7, 9, so the middle value is 5.

3. What is the mode of the data set 3, 7, 7, 2, 9, 7, 4?

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

4. What is the range of the data set 12, 5, 18, 9, 3?

  1. 12
  2. 15
  3. 13
  4. 9
Show the answer
Answer: B. 15
The range is the difference between the greatest and least values in a data set: 18 - 3 = 15.

5. A fair six-sided die is rolled once. What is the probability of rolling a number greater than 4?

  1. 1/3
  2. 2/3
  3. 1/2
  4. 1/6
Show the answer
Answer: A. 1/3
Only 5 and 6 are greater than 4, so 2 of the 6 equally likely outcomes work, giving a probability of 2/6, which simplifies to 1/3.

6. A standard deck has 52 cards, including 13 hearts. What is the probability of drawing a heart from a well-shuffled deck?

  1. 1/4
  2. 1/13
  3. 3/4
  4. 1/2
Show the answer
Answer: A. 1/4
There are 13 hearts out of 52 total cards, so the probability is 13/52, which simplifies to 1/4.

7. In probability, what is the sample space of an experiment?

  1. The probability of failure
  2. The average of all outcomes
  3. The most likely outcome
  4. The set of all possible outcomes
Show the answer
Answer: D. The set of all possible outcomes
The sample space is the complete list of every possible outcome of an experiment, such as {1,2,3,4,5,6} for rolling a die.

8. The probability that it rains tomorrow is 0.3. What is the probability that it does NOT rain tomorrow?

  1. 0.3
  2. 0.7
  3. 0.5
  4. 0.6
Show the answer
Answer: B. 0.7
The probability of an event and its complement must add up to 1, so the probability of no rain is 1 - 0.3 = 0.7.

9. A bag contains 4 red marbles and 6 blue marbles. What is the probability of randomly picking a red marble?

  1. 2/5
  2. 3/5
  3. 1/2
  4. 1/4
Show the answer
Answer: A. 2/5
There are 4 red marbles out of 10 total marbles, so the probability is 4/10, which simplifies to 2/5.

10. Two events are called independent when:

  1. They cannot happen at the same time, so one rules out the other
  2. The outcome of one event does not affect the probability of the other
  3. They always happen together, so knowing one tells you the other will occur
  4. One event causes the other, so the second depends on how the first turns out
Show the answer
Answer: B. The outcome of one event does not affect the probability of the other
Independent events are events where the outcome of one has no effect on the probability of the other, such as flipping a coin twice.

11. A survey recorded these test scores: 70, 85, 90, 85, 60. How many students scored an 85?

  1. 3
  2. 5
  3. 2
  4. 1
Show the answer
Answer: C. 2
Reading through the list of scores, the value 85 appears twice.

12. In a data set, an outlier is best described as:

  1. The value that appears most often in the whole data set
  2. The average found by adding all values and dividing by the count
  3. A value that is much higher or lower than the rest of the data
  4. The value in the exact middle when all the data are put in order
Show the answer
Answer: C. A value that is much higher or lower than the rest of the data
An outlier is a data point that differs greatly from the other values in a set, either much higher or much lower, and can strongly affect statistics like the mean.
Practice this lesson free with instant feedback

Free. New visitors accept the Software License Agreement first.

More free high school sample lessons

See all free sample lessons »
AD
AD
Free Sample Lessons  •  Free Homeschool Curriculum  •  Privacy Policy  •  Terms of Use  •  Contact Us