Question

marks obtained by 5 students 21,22,x,23,20 mean is 20 find x​

Answer 1

• Value of x = 14.

Given :–

• Marks obtain by 5 students :- 21, 22, x, 23 and 20.
• Mean of their marks = 20.

To Find :–

• Value of x.

Solution :–

We know that,

$\orange{ \huge{\star}} \: \blue{ \boxed {\red{mean \: (m) = \dfrac{sum \: of \: the \: terms}{total \: terms} }}} \: \orange{ \huge{ \star}}$

Here the given values are,

• Mean = 20.
• Sum of all the terms = 21 + 22 + x + 23 + 20.
• Total terms = 5.

Now, substitute all the given values in the formula of Mean.

$\longmapsto 20 = \dfrac{21 + 22 + x + 23 + 20}{5}$

$\longmapsto20 = \dfrac{86 + x}{5}$

$\longmapsto 20 \times 5 = 86 + x$

$\longmapsto100 = 86 + x$

$\longmapsto 100 - 86 = x$

$\longmapsto 14 = x$

Hence,

The value of x is 14.

Check :–

Substitute all the values in the formula of mean.

Given values are,

• Mean = 20.
• Sum of the terms = 21 + 22 + 14 + 23 + 20.
• Total term = 5.

So,

$\longmapsto 20 = \dfrac{21 + 22 + 14 + 23 + 20}{5}$

Now, add all the numerator numbers.

$\longmapsto 20 = \cancel\dfrac{100}{5}$

$\longmapsto20 = 20$

Since, we obtain 20 as a mean of their marks.

So, the value of x is 14 is correct.