Question

a student gets 75 82 and 86 marks in an examination how many marks he should get so that his average becomes 85

Answer 1

Answer:

AVG=total marks/total test=85

:. (75+82+86+x)/4=85

243+x=340

x = 97.

Hence he needs 97 marks so that his average becomes 85

Answer 2

Answer:

He should get 12 marks more so that the average becomes 85

Step-by-step explanation:

Given,

The marks obtained by the student in an examination are 75,82,86

To find,

The marks he should get to get an average 85

Solution:

Recall the formula

Average =   $\frac{Sum\ of \ observations }{Total \ number\ of \ observations}$ --------------(1)

Here, the marks obtained = 75,82 and 86

Sum of observations = Total marks obtained = 75+82+86 = 243

Total number of observations = 3

Hence, the average marks obtained by the student  = $\frac{243}{3}$ = 81

Average marks required to get = 85

Since the total number  is 3, from equation (1) we get

Total marks required = Average × Total number

= 85× 3

= 255

Hence to get an average of 85 marks,  the student should get a total mark of 255

∴ Extra marks he should get an average of 85 marks = 255 - 243

= 12marks

He should get 12 marks more so that the average becomes 85

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