Question

Mean of 20 observations is 15. If two observations 3 and 14 are replaced by 8 and 9 respectively, then the new mean will be: a) 14 b) 15 c) 16 d) 17? Please answer this one!​

Answer 1

Answer:

15

Step-by-step explanation:

(14+3)/2=(9+8)/2 so answer

will remain same

Answer 2

The new mean when digits are replace is 15  

Step-by-step explanation:

Given as :

The mean of 20 observation = 15.

i.e $x_1 + x_2 + .............+ x_20$  = 20 × 15

Or, $x_1 + x_2 + 3 + x_4 +.....+ 14........+ x_20$  = 20 × 15

Let The new mean when digits replace = A

Again

3 and 14 are replaced by 8 and 9 respectively

So, The new mean can be written as

$x_1 + x_2 + 8 + x_4 +.....+ 9........+ x_20$  = A

Or,  A = $x_1+x_2+x_3+..........+x_18$ + $x_19 + x_20$

Or,  A = $\dfrac{x_1+x_2+x_3+...........+x_19+x_20}{20}$

Or, A = $\dfrac{300 - 17 +17}{20}$

Or, A = $\dfrac{300}{20}$

∴   A = 15

So, The new mean = A = 15

Hence, The new mean when digits are replace is 15  Answer