Question

a student gets 70% in one subject 80% in the other. to get an overall of 75% how much should get in third subject.

Answer 1

Let the total marks of each subject be = x

Marks of subject 1 = 70% of x

Marks of subject 2 = 80% of x

Overall in 3 subjects = 75% of 3x

Marks in subject 3 should be = 75% of 3x - (70% of x + 80% of x)

= 75% of 3x - 70% of x - 80% of x

= x( 225/100 - 70/100 - 80/100)

= x (75/100)

= 75x/100

= 75%

He should score 75% in the 3rd subject to get a total of 75% overall

Answer 2

Overall percentage is total marks obtained by the student out of total marks of the examination per cent.

Given: The student gets $70$% in one subject and $80$% in another . Total percentage of this student is $75$%.

To Find:

We have to find the value of, percentage the student got in the third subject.

Solution:

According to the problem,

Let percentage of marks obtained by the student in third subject be x

Total percentage of student= (total marks obtained by the student in three subjects ÷ Total marks of the exam) × $100$

$75$ = ($70$+$80$+x) ÷ $300$ × $100$

⇒ $75$ × $300$ ÷ $100$ = $150$ + x

⇒$225$ - $150$ = x

⇒x = $75$%

Final Answer:

The value of marks obtained by the student in third subject is $75%$%.

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