Question

The mean marks of 10 men in a class are 70 Kg, whereas the mean marks of 15 women is 60. The mean marks of all the 25 people are ?

a) 64

b) 60

c) 55

d) 52

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Answer 1

Answer:

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Step-by-step explanation:

=>The mean marks of 10 men = 70

=>Total marks of 10 men = 70 × 10 = 700

=>The mean marks of 15 women = 60

=>Total marks of 15 women = 60 × 15 = 900

marks of 15 women = 60 × 15 = 900∴ Sum of the total marks of 25 people = 700 + 900 = 1600

marks of 15 women = 60 × 15 = 900∴ Sum of the total marks of 25 people = 700 + 900 = 1600∴ The mean marks of all the 25 people =1600/25=64

=> option A is right answer !

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Answer 2

The mean marks of all the 25 people are 64.

Step-by-step explanation:

We are given that the mean marks of 10 men in a class are 70 Kg, whereas the mean marks of 15 women is 60.

AS we know that the formula for finding the mean for group of numbers is given as;

         Mean = $\frac{\sum X}{n}$

where, $\sum X$ = Sum of all values in the data

               n = Total number of observations in the data

• Firstly we are given the mean marks of 10 men in a class, i.e;

         Mean marks of men = $\frac{\sum X_M}{n_M}$

where, $\sum X_M$ = Sum of marks of all 10 men in a class

                 $n_M$ = number of men in a class

           

So,          $70 = \frac{\sum X_M}{10}$

Sum of marks of all 10 men in a class, $\sum X_M$ = $70 \times 10$ = 700

• Also, we are given the mean marks of 15 women in a class, i.e;

         Mean marks of women = $\frac{\sum X_W}{n_W}$

where, $\sum X_M$ = Sum of marks of all 15 women in a class

                 $n_W$ = number of women in a class

           

So,          $60 = \frac{\sum X_W}{15}$

Sum of marks of all 15 women in a class, $\sum X_W$ = $60 \times 15$ = 900

Now, the mean marks of all the 25 people are given by the formula;

         Mean marks of all 25 people = $\frac{\sum X}{n}$

where, $\sum X$ = Sum of all 25 people marks in a class

               n = total number of people in the class

So,  Mean marks of all 25 people = $\frac{\sum X_M + \sum X_W}{n_M + n_W}$

                                                         = $\frac{700+ 900}{10+15}$

                                                         = $\frac{1600}{25}$ = 64

Hence, the mean marks of all the 25 people are 64.