Average
- The average of x numbers is y and average of y numbers is x. Then the average of all the numbers taken together is
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Sum of x numbers = xy
Sum of y numbers = xy∴ Required average = Sum of x numbers + Sum of y numbers = 2xy x + y x + y
Second method to find the required average ,
Here, n1 = x, a1 = y
n2 = y, a2 = x∴ Average = n1a1 + n2a2 n1 + n2
Correct Option: B
Sum of x numbers = xy
Sum of y numbers = xy∴ Required average = Sum of x numbers + Sum of y numbers = 2xy x + y x + y
Second method to find the required average ,
Here, n1 = x, a1 = y
n2 = y, a2 = x∴ Average = n1a1 + n2a2 n1 + n2 Average = xy + yx = 2xy x + y x + y
- 12 kg of rice costing 30 per kg is mixed with 8 kg of rice costing 40 per kg.The average per kg price of mixed rice is
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Total cost price of 20kg of mixed rice = (12 × 30 + 8 × 40) = ₹ 680
∴ Average per kg price = 680 = ₹ 34 20
Second method to find the required average ,
y1 = 12, A1 = 30
y2 = 8, A2 = 40∴ Average = A1y1 + A2y2 y1 + y2
Correct Option: D
Total cost price of 20kg of mixed rice = (12 × 30 + 8 × 40) = ₹ 680
∴ Average per kg price = 680 = ₹ 34 20
Second method to find the required average ,
y1 = 12, A1 = 30
y2 = 8, A2 = 40∴ Average = A1y1 + A2y2 y1 + y2 Average = 30 × 12 + 40 × 8 12 + 8 Average = 360 + 320 20 Average = 680 = ₹ 34 20
