The average of 15 numbers is 80. The average of the first 6 numbers is 72. The…
2025
The average of 15 numbers is 80. The average of the first 6 numbers is 72. The average of the next 6 numbers is 25% more than the average of the first 6 numbers. The 13th number is 8 more than the 15th number, and the 14th number is 10 less than the 15th number. What is the average of the 13th and 14th numbers?
Answer: C. 75.67 — 1. Sum of 15 = 1200. Sum of first 6 = 432. Sum of next 6 = (72 * 1.25) * 6 = 540 2. Sum of 13, 14, 15 = 1200 - (432 + 540) = 228 3. 13th=x+8, 14th=x-10,…
- A.
70.89
- B.
85
- C.
75.67
- D.
80.65
Attempted by 10 students.
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Correct answer: C
1. Sum of 15 = 1200. Sum of first 6 = 432. Sum of next 6 = (72 * 1.25) * 6 = 540
2. Sum of 13, 14, 15 = 1200 - (432 + 540) = 228
3. 13th=x+8, 14th=x-10, 15th=x. (x+8) + (x-10) + x = 228 => 3x = 230 => x=76.67
4. 13th=84.67, 14th=66.67. Average = 75.67