Question 57

Angad was conducting an experiment in which the average of 11 observations came to be 90, while the average of first five observations was 87, and that of the last five was 84. What is the measure of the 6th observation?

Solution

Let the sum of first 5 numbers be x and last five be yand 6th observation be t.

So, by averages formula, we get

x + t+ y = 11*90 = 990 ...-(1)

x = 87*5 = 435

y = 84*5 = 420

So, putting values in equation 1, we get

435 + t + 420 = 990

t = 135

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