600 students took the test on physics and chemistry. 35% students failed in physics and 45% students failed in chemistry and 40% of those who passed in chemistry also passed in physics, then how many students failed in both:

A) 162 B) 138
C) 60 D) None of these

Answer:   D) None of these


                  Physics             Chemistry

Failed           35%                    45%

Passed         65%                    55%

Passed in both = 22% of total student

percentage of students who are passed in any of the physics or chemistry or both =(65+55) - 22 = 98%

So, the percentage of students who are failed in both = 2%

Therefore, total failed (in both subjects) students = 12 


In a competitive examination, the average marks for the entire examination was 60 marks. If 20% of the applicants scored 85 marks and 25% scored 95 marks. What was the average marks of the remaining applicants in the examination ?

A) 60 B) 52
C) 45 D) 35
Answer & Explanation Answer: D) 35


Let the total applicants be 100
Then, 20% got 85 marks

i.e 20  85 = 1700

and 25% got 95 marks

i.e 25  95 = 2375

Now, the remaining applicants are 55 and let the average marks scored by them be x.

 2375 + 1700 + 55 x  =  60  100

 6000 - 4075 = 55x



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4 15

A sales boy is allowed  % discount on the total sales made by him plus a bonus of % on the sales over Rs.12,000.If his total earnings were Rs.2400, then his total sales(in Rs.) are ?

A) Rs.60,145.23 B) Rs.54,285.54
C) Rs.52,147.85 D) Rs.50,589.47
Answer & Explanation Answer: D) Rs.50,589.47


Let the total earnings be Rs.x

Then % of x + % of (x-12,000) =2400

=>   +    =2400

=>  x=50,589.47

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5 140

The population of a city is 415600.It increased by 25% in the first year and decreased by 30% in the second year.What is the population of the city at the end of second year?


As per given data, P = 415600, R1= 25% incresed, R2 = 30% decreased

Population of the city at the end of the second year= 


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9 115

The ratio of earnings of A and B is 4:5. If the earnings of A increase by 20% and the earnings of B decrease by 20%, the new ratio of their earnings becomes 6:5. What are A's earnings?

A) Rs.22,000 B) Rs.27,500
C) Rs. 26,400 D) Cannot be determined
Answer & Explanation Answer: D) Cannot be determined

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57 2131

If the length of a rectangle is increased by 10% and the area is unchanged , then its corresponding breadth must be decreased by?


Suppose length = 100m and breadth = x m

Area = 100 m

New length = 110m and breadth = (x-y% of x)

Then, \inline 110\times (x-\frac{y}{100}x)=100\times x

\inline \Rightarrow \inline 110\times (1-\frac{y}{100})=100

\inline \Rightarrow \inline 1-\frac{y}{100}=\frac{100}{110}

\inline \Rightarrow \frac{y}{100}=1-\frac{100}{110}=\frac{1}{11}

\inline y=\frac{100}{11}=9\frac{1}{10}%

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52 2313