Question

the average score in mathematics of a class increases by 10% if the total marks secured by the number of student who form 20% of the class strength and whoes average score is 48 is not included in the calculation what is average score
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Answer 1

Given :- The average score in mathematics of a class increases by 10% , if the total marks secured by the number of student who form 20% of the class strength and whose average score is 48 is not included in the class . calculation what is average score ?

Solution :-

• Let average score = x
• Let Total students = 100 .

So,

→ average score = (Total marks of class) / (Total students)

→ x = (Total marks) / 100

→ Total marks = 100x .

Now, we have given that, 20% of students whose average score is 48 is not included .

Than,

→ 20% of Total students = (20 * 100)/100 = 20 students.

→ their average score = 48 marks.

so,

→ Total marks not included = 48 * 20 = 960 marks.

Now,

→ Marks left now = (100x - 960) marks.

→ students left = 100 - 20 = 80 students.

Therefore,

→ new average score = (Mark left) / (students left) = {(100x - 960)/80} marks.

given that, average score is increased by 10% .

→ (100x - 960) / 80 = (110x/100)

→ 5(100x - 960) = 4 * 110x

→ 500x - 5 * 960 = 440x

→ 500x - 440x = 5 * 960

→ 60x = 5 * 960

dividing both sides by 60,

→ x = 5 * 16

→ x = 80 (Ans.)

Hence, average score of class is 80 marks.

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