Averages: 15 MCQs with answers
All 15 multiple-choice questions from this kit, free and with no sign-up.
Warm-up · 8 questions
Q1. What is the average of the numbers 4, 8, 12, and 16?
BeginnerShow answer & explanation
10
The sum is $4+8+12+16=40$. There are 4 numbers, so the average is $40 \div 4 = 10$.
Q2. The average of 5 numbers is 12. What is their sum?
BeginnerShow answer & explanation
60
Average = Sum ÷ Count, so Sum = Average × Count = $12 \times 5 = 60$.
Q3. The average of 10, 20, and 30 is:
BeginnerShow answer & explanation
20
Sum = $10+20+30=60$. Count = 3. Average = $60 \div 3 = 20$.
Q4. If the average of 4 numbers is 15, what is their total?
BeginnerShow answer & explanation
60
Total = Average × Count = $15 \times 4 = 60$.
Q5. The average of 2, 4, 6, 8, and 10 is:
BeginnerShow answer & explanation
6
Sum = $2+4+6+8+10=30$. Count = 5. Average = $30 \div 5 = 6$.
Q6. A student scored 70, 80, and 90 in three tests. What is the average score?
BeginnerShow answer & explanation
80
Sum = $70+80+90=240$. Count = 3. Average = $240 \div 3 = 80$.
Q7. The average of a set of numbers is always equal to one of the numbers in the set.
BeginnerShow answer & explanation
False
The average is the sum divided by the count. It may or may not be one of the numbers. For example, the average of 1 and 2 is 1.5, which is not in the set.
Q8. If the average of 10 numbers is 50, then the sum of the numbers is 500.
BeginnerShow answer & explanation
True
Sum = Average × Count = $50 \times 10 = 500$.
Building up · 7 questions
Q9. The average of 6 numbers is 18. If one number is 24, what is the average of the remaining 5 numbers?
IntermediateShow answer & explanation
16.8
Total sum = $18 \times 6 = 108$. Remove 24: remaining sum = $108 - 24 = 84$. Average of 5 numbers = $84 \div 5 = 16.8$.
Q10. The average age of a group of 8 people is 30 years. If a 40-year-old person joins the group, what is the new average age?
IntermediateShow answer & explanation
31.1 years
Original total age = $30 \times 8 = 240$. New total = $240 + 40 = 280$. New count = 9. New average = $280 \div 9 \approx 31.1$ years.
Q11. The average of 5 numbers is 20. If each number is increased by 3, what is the new average?
IntermediateShow answer & explanation
23
Adding 3 to each of 5 numbers increases the total by $5 \times 3 = 15$. New total = $100 + 15 = 115$. New average = $115 \div 5 = 23$.
Q12. The average of 7 numbers is 25. If one number is excluded, the average becomes 24. What is the excluded number?
IntermediateShow answer & explanation
31
Total sum of 7 numbers = $25 \times 7 = 175$. Sum of remaining 6 numbers = $24 \times 6 = 144$. Excluded number = $175 - 144 = 31$.
Q13. The average of 3 numbers is 15. If two of the numbers are 12 and 18, what is the third number?
IntermediateShow answer & explanation
15
Total sum = $15 \times 3 = 45$. Sum of two known numbers = $12 + 18 = 30$. Third number = $45 - 30 = 15$.
Q14. The average of 4 numbers is 30. If one number is 42, what is the average of the remaining 3 numbers?
IntermediateShow answer & explanation
26
Total sum = $30 \times 4 = 120$. Remove 42: remaining sum = $120 - 42 = 78$. Average of 3 numbers = $78 \div 3 = 26$.
Q15. The average of 5 numbers is 16. If one number is removed, the average of the remaining numbers becomes 15. What is the removed number?
IntermediateShow answer & explanation
20
Total sum of 5 numbers = $16 \times 5 = 80$. Sum of remaining 4 numbers = $15 \times 4 = 60$. Removed number = $80 - 60 = 20$.
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