A fraction in reduced form is such that when it is squared and then its numerator is increased by 25% and the denominator is reduced t0 80% it results in of original fraction. The product of the numerator and denominator is :
(A) 6
(B) 12
(C) 10
(D) 7
Solution:
52.
If each edge of a cube is increased by 10% then the percentage increase in its surface area is:
(A) 21%
(B) 19%
(C) 22%
(D) 20%
Solution:
53.
In an examination, 35% of total students failed in Hindi, 45% failed in English and 20% failed in both. Find the percentage of those students who passed in both the subjects ?
(A) 45%
(B) 35%
(C) 20%
(D) 40%
Solution:
Failed students in Hindi = 35% Failed students in English = 45% Student failed in both subject hindi and english = 20% Student only fail in hind = 35 - 20 = 15% Student only fail in English = 45 - 20 = 25% Percentage of passed students in both subjects : = 100 - [ student fail in hindi + student fail in english + student fail in both subject] = [100 - (15 + 25 + 20)] = 40%
54.
When 60 is subtracted from 60% of a number, the result is 60. The number is :
(A) 120
(B) 150
(C) 180
(D) 200
Solution:
Note : In percentage always assume data. Which make your Calculation easier. 60% Let the number = 5x Accounting to the question, ⇒ 5x × - 60 = 60 ⇒ x = ⇒ x = 40 Hence, required number : = 5x = 5 × 40 = 200
55.
Salary of Mohit is 60% more than Vijay. Salary of Vijay is how much percent less than Mohit?
(A) 45%
(B) 42.5%
(C) 47.5%
(D) 37.5%
Solution:
Given: Salary of Mohit is 60% more than Vijay Formula used: Percentage = Calculations: Let the salary of Vijay = Rs. 100 ⇒ So, the salary of Mohit = 100 + 60% of 100 = 100 + 60 = Rs. 160 According to the formula, Hence, the salary of Vijay and less than Mohit by 37.5%
56.
In a factory 60% of the workers are above 30 years and of these 75% are male and the rest are females. If there are 1350 male workers above 30 years, the total number of workers in the factory is :
(A) 3000
(B) 2000
(C) 1800
(D) 1500
Solution:
Given, 60% of work whose age is 30 above 1350 males work whose age is 30 above. 75% of workers are male whose age are 30 above. 25% of female workers whose ages are 30 above. Number of female work whoes age 30 above = total number of work whoes age are 30 above = 1350 + 450 = 1800(60% of the work) Total number of work =
57.
The numbers are respectively ÃÂÃÂ and more than a third number. The as a percentage of the second number is :
(A) 50%
(B) 60%
(C) 75%
(D) 90%
Solution:
Let the third number be Then, first number : = of = Second number : = 125% of = ∴ Required percentage : = % = 90%
58.
A sample of 50 litres of glycerine is found to be adulterated to the extent of 20%. How much pure glycerine should be added to it so as to bring down the percentage of impurity to 5% ?
(A) 155 litres
(B) 150 litres
(C) 150.4 litres
(D) 140 litres
Solution:
Give the amount of solution = 50litres 20% of impurity in a given solution i.e. 40 liters of glycerine and 10 liters of impurities Now to keep the impurity 10 liters and we added glycerine to a solution to bring down impurities level 5%. i.e. 10 is 5% of 200. So we need to added glycerine 'x' amount of glycerine to make solution of 200liters ∴ x = 200 - (40 + 10) = 150 litres of glycerine
59.
If A's salary is 30% more than B's salary, then by what percentage is B's salary less than that of A? (correct to one decimal place)
(A) 17.5%
(B) 23.1%
(C) 25%
(D) 19.7%
Solution:
Given: Salary of A is 30% more than salary of B Calculation: Let the salary of B be 100x Salary of A = 100x + 100x × 30% ⇒ 130x Percentage difference = = = 23.07% ≈ 23.1% ∴ B's salary is 23.1% less than that of A.
60.
A's marks in Biology are 20 less than 25% of the total marks obtained by him in Biology, Maths and Drawing. If his marks in Drawings be 50, what are his marks in Maths ?
(A) 40
(B) 45
(C) 50
(D) Cannot be determined
Solution:
Let B + M + D = Then, B = 25 of - 20 And D = 50 ∴ - 20 + M + 50 = or M = So, marks in Maths cannot be determined.