Question

Mean marks of Salim in 5 subjects is 78. He got 76, 78, 80 and 77 marks respectively in English, Maths , Science, Social science marks. How many marks did Salim get in Hindi?

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Answer 1

Salim got 79 marks in Hindi if Mean marks of Salim in 5 subjects is 78 and he got 76, 78, 80 and 77 marks respectively in English, Maths, Science, Social science marks

Given:

• Mean marks of Salim in 5 subjects is 78.
• Salim got 76, 78, 80 and 77 marks respectively in English, Maths , Science, Social science marks.

To Find:

• Salim marks in Hindi

Solution:

• $\text{Mean}=\dfrac{\text{sum of all the obervations}}{\text{number of the observations}}$

Step 1:

Calculate Total marks by multiplying mean marks with number of subjects.

Total Marks in 5 Subjects = 78 x 5

=> Total Marks in 5 Subjects = 390

Step 2:

Add Marks of  English, Maths , Science, Social science  subjects

Total Marks in 4 Subjects = 76 + 78 + 80 + 77

Total Marks in 4 Subjects = 311

Step 3:

Subtract Marks in 4 subjects ( except Hindi) from Marks in 5 subjects to get marks in Hindi

390 - 311

= 79

Hence,  Salim got 79 marks in Hindi

Answer 2

Given :

Mean marks of Salim in 5 subjects = 78

Marks in English ($M_{English}$) = 76

Marks in Math ($M_{Math}$) = 78

Marks in Science ($M_{Science}$) = 80

Marks in Social Science ($M_{S.Science}$) = 77

To Find :

How much marks did Salim get in Hindi?

Solution :

We know,

Mean of the marks obtained = (Sum of the marks obtained in all subjects ÷ No. of subjects)

∴ Mean Marks = $\frac{Total Marks Obtained}{No. Of Subjects}$

Let the marks obtained in Hindi be 'x'

Total Marks obtained = $M_{English}$ + $M_{Math}$ + $M_{Science}$ + $M_{S.Science}$ + $M_{Hindi}$

                                    = 76 + 78 + 80 + 77 + x

                                    = 311 + x

No. of Subjects = 5

∴     Mean       =  $\frac{311 + x}{5}$

⇒      78          =  $\frac{311 + x}{5}$

⇒  311 + x        =  390

⇒       x            =  390 - 311

∴        x            = 79

Hence, the marks obtained by Salim in Hindi is 79.