Praxis Core Math Practice Test: Statistics and Probability
- Statistics and Probability
- 10 questions
- 14 minutes
Ten statistics and probability questions like those on the Praxis Core Mathematics test. Tip: before finding a median, put the numbers in order; before finding a probability, count all the possible outcomes.
Tap an option to mark your answer. You can change your mind, or tap the same option again to leave the question blank. The correct answers and explanations appear when you finish the test.Tap an option to answer; tap it again to leave the question blank.
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Question 1
What is the mean of 4, 8, 9, 10 and 14?
Correct answer: A
The sum is 45, and 45 ÷ 5 = 9. The value 45 is the total, not the mean.
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Question 2
What is the median of 3, 7, 7, 12, 15 and 20?
Correct answer: B
With six values, the median is the mean of the two middle values: (7 + 12) ÷ 2 = 9.5. The value 7 is the mode.
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Question 3
What is the range of the data set 12, 5, 19, 8, 21?
Correct answer: D
Range = greatest − least = 21 − 5 = 16. Subtracting the first value from the last (21 − 12 = 9) ignores the order of the data.
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Question 4
A bag holds 3 red, 5 blue and 2 green marbles. One marble is picked at random. What is the probability that it is blue?
Correct answer: C
There are 3 + 5 + 2 = 10 marbles and 5 are blue, so the probability is 510 = 12. Dividing by the 8 non-green marbles gives 58 by mistake.
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Question 5
Two fair coins are tossed. What is the probability that both land heads up?
Correct answer: B
The four equally likely outcomes are HH, HT, TH and TT, and only HH works, so the probability is 14. Counting "two heads, one head, no heads" as three equal outcomes gives 13.
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Question 6
A student's first three test scores are 82, 90 and 76. What score does she need on the fourth test to have a mean of exactly 85?
Correct answer: D
Four scores with a mean of 85 must total 4 × 85 = 340. The first three total 248, so she needs 340 − 248 = 92.
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Question 7
Pets owned by 20 students Number of pets Number of students 0 6 1 9 2 4 3 1 What is the mean number of pets per student?
Correct answer: C
Total pets: 0(6) + 1(9) + 2(4) + 3(1) = 20, and 20 ÷ 20 students = 1. The answer 5 comes from dividing 20 by the 4 rows of the table.
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Question 8
In a circle graph of a family's monthly budget, food makes up 15% of the budget. What is the central angle of the food section?
Correct answer: A
A full circle is 360°, and 15% of 360° is 0.15 × 360 = 54°. Using 15° treats the percent as degrees.
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Question 9
Two marbles are drawn, one after the other and without replacement, from a bag with 2 red and 3 blue marbles. What is the probability that both are red?
Correct answer: D
First draw: 25; then 1 red is left among 4 marbles: 14. Multiply: 25 × 14 = 110. The answer 425 assumes the first marble was put back.
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Question 10
The weekly earnings of five part-time workers are $20, $22, $23, $25 and $90. Which statement is true?
Correct answer: B
The mean is 180 ÷ 5 = $36, but the median is the middle value, $23. The outlier of $90 pulls the mean up and leaves the median unchanged.
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