The average of eleven numbers is 54 The average of the first four numbers is 48 and that of the next...........

Quantitative Aptitude (CGL) Average

The average of eleven numbers is 54. The average of the first four numbers is 48 and that of the next four numbers is 25% more

than the average of the first four. The ninth number is 8 greater than the 11^th number and the tenth number is 4 greater than

the 11^thnumber. What is the average of the 9^th and the 10^th numbers?

This questions was previously asked in

SSC CGL 6 June 2019 Shift-3

52.6

54.4

- The overall average of the eleven numbers is 54, so their total is 54 × 11 = 594.

- The average of the first four numbers is 48, so their total is 48 × 4 = 192.

- The average of the next four numbers is 25% more than 48, which is 48 + 12 = 60. So, their total is 60 × 4 = 240.

- Therefore, the sum of the first eight numbers is 192 + 240 = 432.

- The sum of the last three numbers (ninth, tenth, and eleventh) is 594 - 432 = 162.

- Let the eleventh number be x. The ninth number is x + 8, and the tenth number is x + 4.

- Therefore, x + (x + 8) + (x + 4) = 162.

- Simplifying, 3x + 12 = 162, so 3x = 150, and x = 50.

- The ninth number is 50 + 8 = 58, and the tenth number is 50 + 4 = 54.

- The average of the ninth and tenth numbers is (58 + 54) / 2 = 56.

- The correct answer is Option: 3, 56.

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