The average of twelve numbers is 45 5 The averageof the first four numbers is 41 5 and that of the n...........

Quantitative Aptitude (CGL) Average

The average of twelve numbers is 45.5. The averageof the first four numbers is 41.5 and that of the next five numbers is 48. The 10^th

numberis 4 more than the 11^thnumber and 9 more than the 12^th number. Whatis the average of the 10^th and 12^th

numbers?

This questions was previously asked in

SSC CGL 4th March 2020 Shift-1

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47.8

46.6

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Explanation:

The average of 12 numbers = 45.5
Sum of 12 numbers = average x numbers 45.5 x 12 = 546
The average of the first four numbers = 41.5
Sum of first four numbers = 41.5 4 = 166
The average of next five numbers = 48
Sum of next five numbers = 48 x 5 = 240
Sum of the first 9 numbers = sum of first four numbers + sum of next five numbers = 166 + 240 = 406
10th number = 4 + 11th number ---(1)
10th number = 9 + 12th number ---(2)
Sum of the first 9 numbers +10th number + 11th number + 12th number = 546
406 + 10th number + 10th number - 4 + 10th number - 9 = 546
3 x 10th number = 546 - 406 + 4 + 9
3 x 10th number = 153
10th number = 51
From eq(1),
11th number = 10th number - 4 = 51 - 4 = 47
12th number = 10th number - 9 = 51 - 9 = 42

The average of the 10^th and 12^thnumbers = $$\frac{51 + 47 + 42}{3} = 140/3 = 46.6