Question

If the mean of the series is 20, what is the value of X ?
mca
SC
Series : 10, 15, X, 20, 30
(1)
10
(2)
15
(3)
20
(4)
25.​

Answer 1

Answer:

(4) 25

Explanation:

We have,

mean =

$\frac{sum \: of \: all \: observ.}{no. \: of \: obs.}$

$\frac{10 + 15 + x + 20 + 30}{5} \\ = > \frac{75 + x}{5} = 20 \\ = > 75 + x = 100 \\ = > x = 25$

Regards,

kshitij Ampearl

Answer 2

The value of X in this case is 25.Hence,the correct answer is option 4) or 25.

Explanation:

We know that in Statistics,mean or average of any distribution or data set=Sum of all the individual observations in distribution divided by the number of observations.

The data set or distribution here is given as:-

10,15,X,20,30

Sum of all the observations=$(10+15+X+20+30)$=$75+X$

Now,the number of observations in the distribution is 5 and the mean of the series is 20.

Therefore,we can state:-

$(75+X)/5=20$

$75+X=100$

$X=100-75$

$X=25$

Therefore,the missing observation or number in the distribution or series is 25.