1
What is the average of the first 10 natural numbers?
Correct answer: B. 5.5
The sum of 1 to 10 is 55, and 55 ÷ 10 = 5.5. For consecutive numbers the average is also (first + last) ÷ 2 = (1 + 10) ÷ 2.
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Average, Mixture, Alligation and Partnership MCQs
Solved quantitative aptitude MCQs on averages, average speed, mixtures and alligation, and partnership profit sharing, with short worked solutions.
20 MCQsUpdated 27 October 2026
These MCQs cover averages of natural and consecutive numbers, how an average changes when a person joins or leaves, mixtures and alligation, and dividing profit between partners by investment and time.
Work with totals (average × count) whenever a value is added, removed or replaced. For partnership, profit is shared in the ratio of investment multiplied by time.
- 2
The average of 5 numbers is 20. If one number is removed, the average of the remaining numbers is 18. What number was removed?
Correct answer: D. 28
The total of 5 numbers is 100 and the total of the 4 remaining is 72, so the removed number is 100 − 72 = 28.
easy - 3
The average age of 30 students is 15 years. When the teacher's age is included, the average becomes 16 years. What is the teacher's age?
Correct answer: C. 46 years
The new total is 31 × 16 = 496 and the old total is 30 × 15 = 450, so the teacher is 496 − 450 = 46 years old.
medium - 4
A batsman's average after 10 innings is 40. How many runs must he score in the 11th innings to raise his average to 42?
Correct answer: C. 62
He needs 11 × 42 = 462 runs in all and has 10 × 40 = 400, so he must score 62.
medium - 5
What is the average of the first five multiples of 3?
Correct answer: B. 9
The multiples are 3, 6, 9, 12 and 15; their sum is 45 and 45 ÷ 5 = 9 (the middle term).
easy - 6
A car goes from A to B at 60 km/h and returns over the same distance at 40 km/h. What is its average speed for the whole journey?
Correct answer: B. 48 km/h
For equal distances, average speed = 2xy ÷ (x + y) = 2 × 60 × 40 ÷ 100 = 48 km/h, not the simple average of 50.
medium - 7
In what ratio must rice at ₹30 per kg be mixed with rice at ₹40 per kg so that the mixture costs ₹36 per kg?
Correct answer: B. 2 : 3
By alligation, cheaper : dearer = (40 − 36) : (36 − 30) = 4 : 6 = 2 : 3.
medium - 8
A 40-litre mixture contains milk and water in the ratio 3 : 1. How much water must be added to make the ratio 3 : 2?
Correct answer: B. 10 litres
Milk = 30 L and water = 10 L. For 3 : 2, water must be 20 L, so 10 L more water is needed.
medium - 9
A invests ₹20,000 and B invests ₹30,000 in a business for the same period. Out of a profit of ₹10,000, what is A's share?
Correct answer: B. ₹4,000
Profit is shared in the ratio 20,000 : 30,000 = 2 : 3, so A gets 2/5 × 10,000 = ₹4,000.
easy - 10
A invests ₹12,000 for 12 months and B invests ₹18,000 for 8 months. In what ratio should they share the profit?
Correct answer: A. 1 : 1
Capital × time: 12,000 × 12 = 1,44,000 and 18,000 × 8 = 1,44,000, so the ratio is 1 : 1.
medium - 11
A and B invest capital in the ratio 3 : 4 for the same period. If the profit is ₹2,800, what is B's share?
Correct answer: D. ₹1,600
B's share = 4/7 × 2,800 = ₹1,600.
easy - 12
The average of four consecutive even numbers is 27. What is the largest of them?
Correct answer: C. 30
The numbers are 24, 26, 28 and 30 (average 27), so the largest is 30.
medium - 13
The average weight of 8 people rises by 2.5 kg when a new person replaces one who weighs 65 kg. What is the new person's weight?
Correct answer: C. 85 kg
The total rises by 8 × 2.5 = 20 kg, so the new person weighs 65 + 20 = 85 kg.
medium - 14
Sugar costing ₹40 per kg and ₹55 per kg is mixed in the ratio 2 : 1. What is the cost of the mixture per kg?
Correct answer: A. ₹45
Cost of 3 kg = 2 × 40 + 1 × 55 = ₹135, so 1 kg costs 135 ÷ 3 = ₹45.
easy - 15
How many kg of tea at ₹200 per kg must be mixed with 30 kg of tea at ₹250 per kg to get a mixture worth ₹220 per kg?
Correct answer: D. 45 kg
Cheaper : dearer = (250 − 220) : (220 − 200) = 3 : 2. With 30 kg of the dearer tea, the cheaper tea is 30 × 3/2 = 45 kg.
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The average of 11 results is 50. The average of the first 6 is 49 and the average of the last 6 is 52. What is the 6th result?
Correct answer: D. 56
The 6th result is counted in both groups: 6 × 49 + 6 × 52 − 11 × 50 = 294 + 312 − 550 = 56.
hard - 17
The average of 7 consecutive natural numbers is 20. What is the smallest of them?
Correct answer: C. 17
For an odd count of consecutive numbers the average is the middle (4th) number, 20, so the numbers run from 17 to 23.
easy - 18
A, B and C invest in the ratio 2 : 3 : 5 for the same period. What is C's share of a profit of ₹50,000?
Correct answer: D. ₹25,000
C's share = 5/10 × 50,000 = ₹25,000.
easy - 19
A starts a business with ₹45,000. B joins 3 months later with ₹30,000. In what ratio should the profit be shared at the end of the year?
Correct answer: B. 2 : 1
A: 45,000 × 12 = 5,40,000. B: 30,000 × 9 = 2,70,000. The ratio is 2 : 1.
medium - 20
The average temperature from Monday to Wednesday was 37 °C and from Tuesday to Thursday was 34 °C. If Thursday's temperature was 4/5 of Monday's, what was Thursday's temperature?
Correct answer: C. 36 °C
Monday − Thursday = 3 × 37 − 3 × 34 = 9. With Thursday = 0.8 × Monday, 0.2 × Monday = 9, so Monday = 45 °C and Thursday = 36 °C.
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