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Mixtures & Alligation · Question 11 of 60

Question 11

EasyOriginal question

A sports hostel has 30 students with an average weight of 48 kg and 20 students with an average weight of 58 kg. What is the average weight of all 50 students?

Options for question 11

Show the answer and explanation
CorrectNot quiteAnswer B

Correct answer: B

Explanation

  1. Total weight = 30×48+20×58=1440+1160=260030 \times 48 + 20 \times 58 = 1440 + 1160 = 2600 kg.

  2. Average = 260050=52\frac{2600}{50} = 52 kg.

Worth noting

53 kg is the simple average of 48 and 58, which ignores that the groups are of different sizes.

Concept
Combined average of two groups
Typical time
40 s
Your time
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The rule this testsThe alligation rule
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