Averages
Ten quantitative aptitude questions, each marked as you answer.
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What is the average of 86, 94, 29, 95 and 81?
Answer and working
Answer A
Sum = 385. Average = 385 ÷ 5 = 77.
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The average weight of 6 people goes up by 2.5 kg when a new person takes the place of one who weighs 61 kg. What does the new person weigh?
Answer and working
Answer C
The total rises by 6 × 2.5 = 15 kg, so the new person weighs 61 + 15 = 76 kg.
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What is the average of 57, 56, 76, 43 and 18?
Answer and working
Answer D
Sum = 250. Average = 250 ÷ 5 = 50.
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What is the average of 27, 58, 88, 16 and 26?
Answer and working
Answer C
Sum = 215. Average = 215 ÷ 5 = 43.
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What is the average of the first 24 even numbers?
Answer and working
Answer A
The first 24 even numbers add up to 24 × 25 = 600; the average is 25.
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What is the average of the first 51 even numbers?
Answer and working
Answer A
The first 51 even numbers add up to 51 × 52 = 2652; the average is 52.
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The average of 7 numbers is 58. When one number is removed, the average of the rest is 61. Which number was removed?
Answer and working
Answer A
Total of 7 = 7 × 58 = 406. Total of 6 = 6 × 61 = 366. Removed = 406 − 366 = 40.
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Section A has 49 students with an average score of 78; section B has 49 students averaging 54. What is the average score of both sections together?
Answer and working
Answer C
(49 × 78 + 49 × 54) ÷ 98 = 6468 ÷ 98 = 66. The plain mean of 78 and 54 ignores the sizes of the sections.
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What is the average of the first 16 even numbers?
Answer and working
Answer C
The first 16 even numbers add up to 16 × 17 = 272; the average is 17.
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Section A has 50 students with an average score of 61; section B has 25 students averaging 52. What is the average score of both sections together?
Answer and working
Answer C
(50 × 61 + 25 × 52) ÷ 75 = 4350 ÷ 75 = 58. The plain mean of 61 and 52 ignores the sizes of the sections.
More quantitative aptitude: Percentages, Profit, loss and discount, Simple interest, Compound interest, Ratio and proportion, Problems on ages.