Percentage
- The average marks obtained in a class of 50 students is 70%. The average of first 25 is 60% and that of 24 is 80%. What is the marks obtained by the last student?
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Total marks of 50 students = 50 × 70 = 3500
Total marks of 25 students = 25 × 60 = 1500
Total marks of 24 students = 24 × 80 = 1920
∴ Marks obtained by last student = 3500 – 1500 – 1920
= 80 i.e, 80%Correct Option: C
Total marks of 50 students = 50 × 70 = 3500
Total marks of 25 students = 25 × 60 = 1500
Total marks of 24 students = 24 × 80 = 1920
∴ Marks obtained by last student = 3500 – 1500 – 1920
= 80 i.e, 80%
- Two students appeared for an examination. One of them secured 9 marks more than the other and his marks were 56% of the sum of their marks. The marks obtained by them are
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Let marks obtained by the first student be x.
∴ Marks obtained by the second
student = x – 9
According to the question,
x = 56% of (x + x – 9)⇒ x = (2x - 9) × 56 100
⇒ 100x = 112x – 504
⇒ 112x – 100x = 504
⇒ 12x = 504⇒ x = 504 = 42 12
∴ Marks obtained by the second student = 42 – 9 = 33Correct Option: C
Let marks obtained by the first student be x.
∴ Marks obtained by the second
student = x – 9
According to the question,
x = 56% of (x + x – 9)⇒ x = (2x - 9) × 56 100
⇒ 100x = 112x – 504
⇒ 112x – 100x = 504
⇒ 12x = 504⇒ x = 504 = 42 12
∴ Marks obtained by the second student = 42 – 9 = 33
- An engineering student has to secure 25% marks to pass. He gets 47 and fails by 43 marks. What are the maximum marks of the examination ?
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Maximum marks of examination = x (let)
According to the question,
25% of x = 47 + 43= x × 25 = 90 100 ⇒ x = 90 ⇒ x = 4 × 90 = 360 4 Correct Option: C
Maximum marks of examination = x (let)
According to the question,
25% of x = 47 + 43= x × 25 = 90 100 ⇒ x = 90 ⇒ x = 4 × 90 = 360 4
- An examiner has to secure 40% marks to pass an examination. He secures 180 marks and fails by an equal number of marks. The total number of marks in the examination is
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NA
Correct Option: A
NA
- Salary of a person is first increased by 20%, then it is decreased by 20%. Percentage change in his salary is :
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Using Rule 4,
Change in his salary= 
20 - 20 - 20 × 20 
% 100 = - 400 % = – 4% 100
i.e. 4% decrease
Note : If A is first increased by x% and then decreased by y% the net % change= x - y - xy % 100
If the result is positive, the change indicates increase and if the result is negative, the change indicates decrease.Correct Option: A
Using Rule 4,
Change in his salary= 20 - 20 - 20 × 20 % 100 = - 400 % = – 4% 100
i.e. 4% decrease
Note : If A is first increased by x% and then decreased by y% the net % change= x - y - xy % 100
If the result is positive, the change indicates increase and if the result is negative, the change indicates decrease.
