Average
- Six tables and twelve chairs were bought for ₹ 7,800. If the average price of a table is ₹ 750, then the average price of a chair would be
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Here , Six tables and twelve chairs bought = ₹ 7,800
The average price of a table = ₹ 750
Average cost of a chair = ₹ y , then
y × 12 + 6 × 750 = 7800
⇒ 12y = 7800 – 4500 = 3300Correct Option: B
Here , Six tables and twelve chairs bought = ₹ 7,800
The average price of a table = ₹ 750
Average cost of a chair = ₹ y , then
y × 12 + 6 × 750 = 7800
⇒ 12y = 7800 – 4500 = 3300⇒ y = 3300 = 275 12
- 4 boys and 3 girls spent ₹ 120 on the average, of which boys spent ₹ 150 on the average. Then the average amount spent by the girls is
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The average of 4 boys and 3 girls on expenditure = ₹ 120
Total expenditure = 120 × 7 = Rs. 840
The average of 4 boys on expenditure = ₹ 150
Total expenditure of 4 boys = 150 × 4 = 600
Total expenditure of 3 girls = Total expenditure - Total expenditure of 4 boys
Total expenditure of 3 girls = 840 – 600 = 240Correct Option: A
The average of 4 boys and 3 girls on expenditure = ₹ 120
Total expenditure = 120 × 7 = Rs. 840
The average of 4 boys on expenditure = ₹ 150
Total expenditure of 4 boys = 150 × 4 = 600
Total expenditure of 3 girls = Total expenditure - Total expenditure of 4 boys
Total expenditure of 3 girls = 840 – 600 = 240∴ Their average expenditure = 240 = 80 3
- The average weight of five persons sitting in a boat is 38 kg. The average weight of the boat and the persons sitting in the boat is 52 kg. What is the weight of the boat ?
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Given that , The average weight of five persons sitting in a boat = 38 kg.
Sum of weight of five persons = 5 × 38 = 190
The average weight of the boat and the persons sitting in the boat = 52 kg.
Sum of weight of the boat and five persons = 6 × 52 = 312Correct Option: B
Given that , The average weight of five persons sitting in a boat = 38 kg.
Sum of weight of five persons = 5 × 38 = 190
The average weight of the boat and the persons sitting in the boat = 52 kg.
Sum of weight of the boat and five persons = 6 × 52 = 312
∴ Weight of the boat = Sum of weight of the boat and five persons – Sum of weight of five persons
Weight of the boat = 312 – 190 = 122 kg
- The average of 10 numbers is 7. If each number is multiplied by 12, then the average of the new set of numbers will be
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As we know that If each number is multiplied by a certain number, then the average is also multiplied by that number.
Given , The average of 10 numbers = 7Correct Option: D
As we know that If each number is multiplied by a certain number, then the average is also multiplied by that number.
Given , The average of 10 numbers = 7
∴ Required average = 7 × 12 = 84
- A student was asked to find the arithmetic mean of the following 12 numbers :
3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and y
He found the mean to be 12. The value of y will be :
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As we know that ,
Average or Mean = Sum of quantities Total number of quantities Mean = 3 + 11 + 9 + 7 + 15 + 13 + 8 + 19 + 17 + 21 + 14 + y 12
According to question,
Correct Option: B
As we know that ,
Average or Mean = Sum of quantities Total number of quantities Mean = 3 + 11 + 9 + 7 + 15 + 13 + 8 + 19 + 17 + 21 + 14 + y 12
According to question,12 = 137 + y 12
∴ 137 + y = 144
∴ y = 144 - 137 = 7
