1. Two numbers are less than third number by 30% and 37% respectively. How much percent is the second number less than by the first
A. 8%
B. 9%
C. 10%
D. 11%
Answer: Option C
Explanation:
Let the third number is x.
then first number = (100-30)% of x
= 70% of x = [latex]\frac{7x}{10}[/latex]
The second number is ([latex]\frac{63x}{100}[/latex])
Difference = [latex]\frac{7x}{10}[/latex] - [latex]\frac{63x}{100}[/latex] = [latex]\frac{7x}{10}[/latex]
So the required percentage is, the difference is what percent of the first number
=> ([latex]\frac{7x}{100}[/latex] * [latex]\frac{10}{7x}[/latex])% = 10%
2. In an examination, 34% of the students failed in mathematics and 42% failed in English. If 20% of the students failed in both the subjects, then find the percentage of students who passed in both the subjects.
A. 40%
B. 42%
C. 44%
D. 46%
Answer: Option C
Failed in mathematics, n(A) = 34
Failed in English, n(B) = 42
n(A∪B) = n(A) + n(B) − n(A∩B) = 34 + 42 − 20 = 56 Failed in either or both subjects are 56Percentage passed = (100 − 56)% = 44%
3. Out of 450 students of a school, 325 play football, 175 play cricket and 50 neither play football nor cricket. How many students play both football and cricket ?
A. 75
B. 100
C. 125
D. 150
Answer: Option B
Explanation:
Students who play cricket, n(A) = 325
Students who play football, n(B) = 175
Total students who play either or both games,
= n(A∪B) = 450 − 50 = 400Required Number, n(A∩B) = n(A) + n(B) − n(A∪B) = 325 + 175 − 400 = 100
4. The teacher took the exam for English, the average for the entire class was 80 marks. If we say that 10% of the students scored 95 marks and 20% scored 90 marks then calculate average marks of the remaining students of the class.
Answer: Option C
Explanation:
Lets assume that total number of students in class is 100 and required average be x.
Then from the given statement we can calculate :
(10 * 95) + (20 * 90) + (70 * x) = (100 * 80)
=> 70x = 8000 - (950 + 1800) = 5250
=> x = 75.
5. How many liters of pure acid are there in 8 liters of a 20% solution
A. 1.5
B. 1.6
C. 1.7
D. 1.8
Answer: Option B
Explanation:
Question of this type looks a bit typical, but it is too simple, as below...
It will be 8 * [latex]\frac{20}{100}[/latex] = 1.6