Q. Out of seven given numbers, the average of the first four numbers is 4 and that of the last four numbers is also 4. If the average of all the seven numbers is 3, fourth number is
✅ Correct Answer: (D)
11
Explanation: Average of the first four numbers = 4
Sum of the first four numbers = 4 × 4
Average of the last four numbers = 4
Sum of the last four numbers = 4 × 4
Average of all the seven numbers = 3
Sum of the seven numbers = 3 × 7
∴ Fourth number = ( Sum of the first four numbers + Sum of the last four numbers ) - Sum of the seven numbers
Fourth number = (4 × 4 + 4 × 4 – 3 × 7)
Fourth number = (16 + 16 - 21) = 11
Explanation by: Parvesh Kanani
Average of the first four numbers = 4
Sum of the first four numbers = 4 × 4
Average of the last four numbers = 4
Sum of the last four numbers = 4 × 4
Average of all the seven numbers = 3
Sum of the seven numbers = 3 × 7
∴ Fourth number = ( Sum of the first four numbers + Sum of the last four numbers ) - Sum of the seven numbers
Fourth number = (4 × 4 + 4 × 4 – 3 × 7)
Fourth number = (16 + 16 - 21) = 11
Sum of the first four numbers = 4 × 4
Average of the last four numbers = 4
Sum of the last four numbers = 4 × 4
Average of all the seven numbers = 3
Sum of the seven numbers = 3 × 7
∴ Fourth number = ( Sum of the first four numbers + Sum of the last four numbers ) - Sum of the seven numbers
Fourth number = (4 × 4 + 4 × 4 – 3 × 7)
Fourth number = (16 + 16 - 21) = 11