Question

The mean marks of 100 students was found to be 40. If by mistake, the tabular took 08,29and 18 Instead of correct marks 88,92and 81 find the correct mean

Answer 1

The answer is in the image. Hope you understand this..

Answer 2

Answer:

42.06

Step-by-step explanation:

The mean marks of 100 students was found to be 40.

$Mean = \frac{\text{Sum of all observations}}{\text{Total no. of observations}}$

$40 = \frac{\text{Sum of scores}}{100}$

$40 \times 100 =\text{Sum of scores}$

$4000 =\text{Sum of scores}$

Now we are given that  the tabular took 08, 29 and 18 Instead of correct marks 88,92 and 81

So, New Sum = Sum-(wrong observations) +(correct observations)

                    = 4000-(8+29+18) +(88+92+81)

                    = 4000-55 +261

                    = 4206

Now $\text{New Mean} = \frac{\text{New Sum}}{\text{Total no. of Students}}$

$\text{New Mean} = \frac{4206}{100}$

$\text{New Mean} = 42.06$

Hence the new mean is 42.06