Average Practice Questions

5 questions per page • Detailed step-by-step solutions

Question 11
Medium
The average of 50 numbers is 33. If each of the first 25 numbers is increased by 9 and each of the remaining 25 numbers is decreased by 2, what is the new average?
A 40
B 36.5
C 29.5
D 37.5
Correct Answer: B

Explanation:

Step 1: Original total = 50 × 33 = 1650. Step 2: Increase = 25 × 9 = 225; decrease = 25 × 2 = 50; new total = 1650 + 225 − 50 = 1825. Step 3: New average = 1825 ÷ 50 = 36.5.
Question 12
Easy
The average weight of 47 boys is 52 kg and that of 47 girls is 46 kg. What is the average weight of all 94 children?
A 50 kg
B 48 kg
C 49 kg
D 51 kg
Correct Answer: C

Explanation:

Step 1: Total of group 1 = 47 × 52 = 2444; total of group 2 = 47 × 46 = 2162. Step 2: Combined total = 2444 + 2162 = 4606 for 47 + 47 = 94 members. Step 3: Combined average = 4606 ÷ 94 = 49.
Question 13
Medium
The average temperature of Monday, Tuesday, Wednesday and Thursday was 36°C, and that of Tuesday, Wednesday, Thursday and Friday was 37.5°C. If Monday's temperature was 28°C, what was Friday's temperature?
A 22°C
B 34°C
C 29.5°C
D 35°C
Correct Answer: B

Explanation:

Step 1: Mon + Tue + Wed + Thu = 4 × 36 = 144. Step 2: Tue + Wed + Thu + Fri = 4 × 37.5 = 150. Step 3: Subtracting, Mon − Fri = 144 − 150 = −6, so Fri = 28 + 6 = 34°C.
Question 14
Easy
A car travels from P to Q at 10 km/h and returns from Q to P at 15 km/h. What is its average speed for the whole journey?
A 12 km/h
B 12.5 km/h
C 14 km/h
D 10 km/h
Correct Answer: A

Explanation:

Step 1: Let each half be 30 km (LCM of 10 and 15). Step 2: Time = 30/10 + 30/15 = 3 + 2 = 5 h for 60 km. Step 3: Average speed = total distance ÷ total time = 60 ÷ 5 = 12 km/h.
Question 15
Medium
A person covers three equal distances at 20 km/h, 10 km/h and 60 km/h respectively. What is his average speed for the whole journey?
A 30 km/h
B 20 km/h
C 18 km/h
D 16 km/h
Correct Answer: C

Explanation:

Step 1: Let each distance = 60 km (LCM of 20, 10, 60). Step 2: Times = 3 + 6 + 1 = 10 h for 180 km. Step 3: Average speed = 180 ÷ 10 = 18 km/h.