Question

The mean of 20 observations of a series is 18.7. If from each of the
observations 3 is subtracted and then multiplied by 2, the mean of the
new observations is
(a) 32.4
(16) 31.4
(c) 30.4
(d) None​

Answer 1

Answer:

the mean of new set of observation is 31.4

Answer 2

$\huge\bf\blue{31.4}$ is Answer

$\bf\orange{Explanation-}$

✢$\sf\red{Sum~of~20~Observations=20×18.7}$

✢$\sf\pink{Sum~of~20~Observation=374}$

✢$\sf\green{Mean~of~New~Observation =\frac{2×(374 -60)}{20}}$

✢$\sf\gray{Mean~of~New~Observation=31.4}$