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SSC Selection Post 2022 PYQ — Question 55

SSC Selection Post - Matriculation Level - 05 Aug 2022 - Shift 3 • Quantitative Aptitude • Q55

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How much chicory at Rs.5 per kg should be added to 10 kg of coffee at Rs.12 per kg so that the mixture will be worth Rs.7.50 per kg?

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Correct answer: A

Explanation

The correct answer is option 1 i.e. 18 kg. 

Weighted average = (w1×r1+w2×r2)(w1+w2)\frac{(w_1 \times r_1 + w_2 \times r_2)}{(w_1 + w_2)}

w1=10,r1=12,r2=5,R=7.50w_1 = 10, r_1 = 12, r_2 = 5 ,R = 7.50

7.50=(10×12+w2×5)(10+w2) 7.50 = \frac{(10 \times 12 + w_2 \times 5)}{(10 + w_2)}

75+7.50w2=120+5w275 + 7.50w_2 = 120 + 5w_2

2.50w2=452.50w_2 = 45

w2=18 w_2 = 18