The average of 8 numbers is 47, and the average of the first three numbers is 39, and the average of the next two numbers is 48, the seventh number is 2 more than the sixth number and 3 less than the eighth number. What is the average of the sixth and the seventh number?
The average of 8 numbers is 47, and the average of the first three numbers is 39, and the average of the next two numbers is 48, the seventh number is 2 more than the sixth number and 3 less than the eighth number. What is the average of the sixth and the seventh number? Correct Answer 53
Given:
Average of all eight numbers = 47
Average of first three numbers = 39
Average of next two numbers = 48
Seventh number is 2 more than sixth number
Seventh number is 3 less than eighth number
Formula used:
Average = Sum of all the terms/Number of all the terms
Calculation:
Sum of all numbers = 47 × 8 = 376
Sum of first three numbers = 39 × 3 = 117
Sum of next two numbers = 48 × 2 = 96
Let seventh number be x, sixth number be x – 2, and eighth number be x + 3
Sum of all numbers = 117 + 96 + x – 2 + x + x + 3
⇒ 214 + 3x = 376
⇒ 3x = 162
⇒ x = 54
Seventh number = 54
Sixth number = 54 – 2 = 52
Average of sixth and seventh number = (54 + 52)/2
∴ The average of sixth and seventh number is 53