The average of 24 numbers is 56. The average of the first 10 numbers is 71.7 and that of the next 11 numbers is 42. The next three numbers (i.e., 22nd, 23rd and 24th ) are in the ratio 1/2 : 1/3 : 5/12. What is the average of the 22nd and 24th numbers?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e 60.5
| Understanding | Application |
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We will use the concepts of averages. |
The sum of the first 10 terms will be ⇒ 10 × 71.7 = 717 The sum of the next 11 terms = 11 × 42 = 462 The sum of 24 numbers are = 24 × 56 = 1344 The sum of 22nd, 23rd & 24th numbers are = 1344 - 717 - 462 = 165 Let the 22nd, 23rd & 24th terms be x/2, x/3 & 5x/12 ⇒ x/2 + x/3 + 5x/12 = 165 ⇒ 5x/4 = 165 ⇒ x = 132 The average of 22nd & 24th term will be ⇒ (x/2 + 5x/12)/2 ⇒ {66 + 55)/2 = 60.5 |