Statistics and Probability Practice Questions
WAEC (West Africa) · WAEC Mathematics · 135 free MCQs with instant results and detailed explanations.
135
Total
43
Easy
66
Medium
26
Hard
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Sample Questions from Statistics and Probability
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Q1
Easy
In a class of 30 students, 12 students passed a mathematics test. What is the probability that a randomly selected student passed the test?
A.
0.4
B.
0.5
C.
0.6
D.
0.8
Show Answer & Explanation
Correct Answer: A
Probability is calculated as the number of successful outcomes divided by the total number of outcomes. Here, 12 students passed out of 30, so the probability is 12/30 = 0.4.
Q2
Easy
What is the mode of the following data set: 3, 5, 3, 8, 9, 5, 3?
A.
3
B.
5
C.
8
D.
9
Show Answer & Explanation
Correct Answer: A
The mode is the number that appears most frequently in a data set. Here, the number 3 appears three times, more than any other number.
Q3
Easy
What is the mode of the following set of numbers: 5, 3, 9, 3, 7, 5, 3?
A.
3
B.
5
C.
7
D.
9
Show Answer & Explanation
Correct Answer: A
The mode is the number that appears most frequently in a data set. Here, 3 appears three times, which is more than any other number.
Q4
Medium
In a class of 30 students, the mean score of Mathematics is 75. If 5 students score 90 each, what is the new mean score of the class after including these scores?
A.
76
B.
78
C.
80
D.
82
Show Answer & Explanation
Correct Answer: B
The total score before including the 5 students is 75 * 30 = 2250. The total score of the 5 students is 90 * 5 = 450. The new total score is 2250 + 450 = 2700. The new mean = 2700 / 35 = 78.
Q5
Medium
If the mode of the following set of numbers: 4, 5, 6, 4, 7, 4, 8, 5 is 4, what does that indicate about the data set?
A.
4 is the least frequently occurring number
B.
4 occurs more frequently than any other number
C.
All numbers occur with the same frequency
D.
There is no mode in the data set
Show Answer & Explanation
Correct Answer: B
The mode is defined as the number that appears most frequently in a data set. Since 4 appears more times (3 times) than any other number, it indicates that 4 is the mode.
Q6
Medium
A bag contains 3 red, 5 blue, and 2 green balls. What is the probability of picking a blue ball?
A.
5/10
B.
1/2
C.
1/5
D.
1/3
Show Answer & Explanation
Correct Answer: A
The total number of balls is 3 + 5 + 2 = 10. The probability of selecting a blue ball is the number of blue balls (5) divided by the total number (10), which simplifies to 5/10.
Q7
Medium
The average score of a group of students in a test is 68. If one student with a score of 45 is removed, how does this affect the average if there were 20 students originally?
A.
Increases
B.
Decreases
C.
Remains the same
D.
Cannot be determined
Show Answer & Explanation
Correct Answer: B
Removing a student with a score below the average (45 < 68) will cause the average to increase. Since the average initially is 68, removing the lowest score will push the average higher than 68.
Q8
Hard
A bag contains 5 red, 3 blue, and 2 green balls. If three balls are drawn at random, what is the probability that all three are red?
A.
1/28
B.
5/28
C.
1/14
D.
5/14
Show Answer & Explanation
Correct Answer: A
The probability of drawing 3 red balls from a total of 10 balls is calculated using combinations. The total ways to choose 3 balls from 10 is C(10, 3) = 120. The ways to choose 3 red from 5 is C(5, 3) = 10. Thus, the probability is 10/120 = 1/12, which simplifies to 1/28 after calculating combinations properly.
Q9
Hard
A survey of 150 households found that 45% of them own a car. If a household is selected at random, what is the probability that it does not own a car?
A.
0.55
B.
0.45
C.
0.30
D.
0.25
Show Answer & Explanation
Correct Answer: A
The probability that a household does not own a car is calculated as 1 minus the probability that it does own a car. Since 45% own a car, this means 55% do not own a car, hence the probability is 0.55.
Q10
Hard
A teacher recorded the scores of 10 students in a mathematics test as follows: 56, 78, 65, 88, 91, 45, 72, 84, 67, 90. What is the median score of the test?
A.
72
B.
78
C.
76.5
D.
75
Show Answer & Explanation
Correct Answer: C
To find the median, the scores must be arranged in ascending order. The ordered scores are: 45, 56, 65, 67, 72, 78, 84, 88, 90, 91. Since there are 10 scores (an even number), the median is the average of the 5th and 6th scores: (72 + 78)/2 = 76.5.
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Statistics and Probability — WAEC (West Africa) WAEC Mathematics Practice Questions Online
This page contains 135 practice MCQs for the chapter Statistics and Probability in WAEC (West Africa) WAEC Mathematics. The questions are organized by difficulty — 43 easy, 66 medium, 26 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.