Question

The average of first 40 results is 40, and that of next 60 results is 60. What is the average of all 100 results?
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Answer 1

Answer:

52

Explanation:

Average = (sum of observations)/number

Average of first 40 results is 40:

=> 40 = (sum of 40 results)/40

=> 40*40 = 1600 = sum of 40 results

Average of next 60 results is 60:

=> 60 = (sum of 60 results)/60

=> 60*60 = 3600 = sum of 60 results

Therefore,

Average of all 100 results is :

=> (sum of 40 + 60 results)/100

=> (1600 + 3600)/100

=> 5200/100

=> 52

Answer 2

Given :-

Average of first 40 results is 40, and that of next 60 results is 60

To Find :-

The average of all 100 results

Solution :-

We know that

$\bf\red{Average = \dfrac{Sum \; of \; observation}{No. \; of \; observation}$

For the first 40 results

Let the sum be x

$\sf 40 = \dfrac{x}{40}$

$\sf 40 \times 40 = x$

$\sf 1600 = x$

For the last 60 result

Sum = y

$\sf 60 = \dfrac{y}{60}$

$\sf 60 \times 60 = y$

$\sf 3600 = y$

$\bf \pink{Total \; Avg. = \dfrac{x+y}{100}}$

$\sf Total \; Average = \dfrac{1600 + 3600}{100}$

$\sf Total\; average = \dfrac{5200}{100}$

$\sf Total \; Average = 52$