Question

The mean of 5 numbers is 18 if one number is excluded there mean becomes 16 what will be the student number

Answer 1

The student number is 26.

Step-by-step explanation:

We are given that the mean of 5 numbers is 18 and if one number is excluded there mean becomes 16.

Let the student number be $x$.

Firstly, as we know that;

        Mean = Sum of all values ÷ Total no. of values

Since, mean of 5 numbers is 18, i.e.;

             18 = Sum of all 5 numbers ÷ 5

So, Sum of all 5 numbers = $18 \times 5$ = 90

Now, we are given that one number is excluded and there mean becomes 16, which means;

             New mean = $\frac{90-x}{5-1}$     {As now no. of values will be four because one

                                                  number is excluded}

                         $16 = \frac{90-x}{4}$

                   $90-x = 16 \times 4$

                        $x$ = 90 - 64 = 26

Therefore, the student number is 26.

Other links for similar type questions;

https://brainly.in/question/10874000

https://brainly.in/question/6202169

Answer 2

Correct question:

The mean of 5 numbers is 18. If one number is excluded, their mean becomes 16. What is the excluded number?

Solution:

Number of observations = 5

Mean = 18

$\tt{\bar{x} = 18}$

=> $\tt{\frac{(x_{1} + x_{2} + x_{3} + x_{4} + x_{5})}{5} = 18}$

=> $\tt{x_{1} + x_{2} + x_{3} + x_{4} + x_{5} = 90}$

If one number is excluded:

$\tt{\bar{x} = 16}$

=> $\tt{\frac{(x_{1} + x_{2} + x_{3} + x_{4})}{4} = 16}$

=> $\tt{x_{1} + x_{2} + x_{3} + x_{4} = 64}$

Excluded number = 90 - 64 = 26

Thus, answer is 26.

___________