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Averages · Question 34 of 62

Question 34

MediumOriginal question

A dairy mixes cow milk costing ₹56 per litre with buffalo milk costing ₹72 per litre, so that the mixture costs ₹66 per litre. If 30 litres of buffalo milk are used, how many litres of cow milk are used?

Options for question 34

Show the answer and explanation
CorrectNot quiteAnswer A

Correct answer: A

Explanation

  1. Cow milk is 66−56=1066 - 56 = 10 below ₹66; buffalo milk is 72−66=672 - 66 = 6 above it.

  2. Cow : buffalo = 6:10=3:56 : 10 = 3 : 5.

  3. Cow milk = 35×30=18\frac{3}{5} \times 30 = 18 litres.

Worth noting

Check: (18×56+30×72)÷48=3,168÷48(18 \times 56 + 30 \times 72) \div 48 = 3{,}168 \div 48 = ₹66. Using the ratio as 5:35 : 3 gives 50 litres.

Concept
Mixture quantities from a target average price
Typical time
60 s
Your time
—
The rule this testsWeighted average
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