The average of fourteen numbers is 46. The average of first five is 43 and that of last six numbers is 49.5. The sixth and seventh numbers are respectively 4 and 8 greater than the eighth number. What is the average of sixth and seventh numbers?
The average of fourteen numbers is 46. The average of first five is 43 and that of last six numbers is 49.5. The sixth and seventh numbers are respectively 4 and 8 greater than the eighth number. What is the average of sixth and seventh numbers? Correct Answer 46
Average of 14 numbers = 46
Sum of 14 numbers = 46 × 14 = 644
Average of first 5 numbers = 43
Sum of first 5 numbers = 43 × 5 = 215
Average of last six numbers = 49.5
Sum of last six numbers = 49.5 × 6 = 297
Sum of 6th, 7th and 8th number is = 644 – 215 – 297 = 132
Let the eight number be x, then
Sixth and seventh numbers are (x + 4) and (x + 8) respectively.
x + 4 + x + 8 + x = 132
3x + 12 = 132
3x = 132 – 12
x = 120/3
x = 40
Sixth number = 40 + 4 = 44
Seventh number = 40 + 8 = 48
Average of sixth and seventh numbers = (44 + 48)/2 = 46
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Feb 20, 2025