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The average of 7 numbers is 28. The average of first three of them is 23 and the last three of them is 42. Then the fourth number is:
- A3
- B2
- C1
- D0
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CCommunity
We know that, Average = Sum of all quantities/number of quantities
Average of 7 numbers = 28
∴ sum of all numbers = 28 × 7 = 196
Average of first 3 numbers is 23.
Sum of first 3 numbers = 3 × 23 = 69
Average of last 3 numbers os 42.
Sum of last 3 numbers = 3 × 42 = 126
4th number = 196 – 69 – 126 = 1
Average of 7 numbers = 28
∴ sum of all numbers = 28 × 7 = 196
Average of first 3 numbers is 23.
Sum of first 3 numbers = 3 × 23 = 69
Average of last 3 numbers os 42.
Sum of last 3 numbers = 3 × 42 = 126
4th number = 196 – 69 – 126 = 1