Q. 4 boys and 3 girls spent 120 Rs. on the average, of which boys spent 150 Rs. on the average. Then what would be the average amount spent by the girls is :
Answer: 80 Rs
Notes: Total expenditure $latex = 120 \times 7 = 840\ Rs.$ Total expenditure of 4 boys $latex = 150 \times 4 = 600\ Rs.$ Total expenditure of 3 girls $latex = 840 - 600 = 240\ Rs.$ ∴ Their average expenditure $latex = \frac{240}{3} = 80\ Rs.&s=1$ Hence option [B] is correct answer.

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