1.
Due to the reduction in the price of petrol by 30%, a customer can buy 15 liters more for the same amount. Find the original quantity of petrol he used to buy?
Correct Answer
B. 35 L
Explanation
The original quantity of petrol the customer used to buy was 35 liters. This can be determined by calculating the difference in the price of petrol before and after the reduction. Since the price decreased by 30%, the customer can now buy 15 liters more for the same amount. Therefore, the customer initially bought 35 liters of petrol.
2.
Raju invested 20% of his money in mutual funds, 20% of the rest in gold, and spent 25% of the remaining for his kid's school fees. What percentage of the original sum was he left with?
Correct Answer
C. 48 %
Explanation
Raju invested 20% of his money in mutual funds, which means he has 80% of his original amount left. He then invested 20% of the remaining amount in gold, so he has 80% * 80% = 64% of his original amount left. He spent 25% of the remaining amount on his kid's school fees, which leaves him with 75% of the remaining amount. Therefore, he is left with 64% * 75% = 48% of the original sum.
3.
In a class of 300 students, the number of boys is twice that of girls. If 50% of the boys and 48% of girls appear in the examination, how many students did not appear?
Correct Answer
C. 152
Explanation
In the given class, let the number of girls be x. According to the question, the number of boys is twice that of girls, so the number of boys is 2x.
The total number of students in the class is x (girls) + 2x (boys) = 3x.
If 50% of the boys and 48% of girls appear in the examination, the number of boys who appeared is 0.5 * 2x = x, and the number of girls who appeared is 0.48 * x = 0.48x.
The total number of students who appeared is x + 0.48x = 1.48x.
The number of students who did not appear is the total number of students minus the number of students who appeared, which is 3x - 1.48x = 1.52x.
Since the total number of students is 300, we can set up the equation 3x = 300 and solve for x.
x = 100.
Substituting x back into the equation for the number of students who did not appear, we get 1.52 * 100 = 152. Therefore, the correct answer is 152.
4.
If the length and breadth of a rectangle are increased by 10% and 50% respectively. Then the percentage increase in the area of the rectangle is
Correct Answer
B. 65 %
Explanation
When the length and breadth of a rectangle are increased by 10% and 50% respectively, the new length and breadth become 1.1 times and 1.5 times the original length and breadth. Therefore, the new area of the rectangle is 1.1 times 1.5, which is 1.65 times the original area. To find the percentage increase in the area, we subtract 1 from 1.65 and multiply by 100. This gives us 65%, which means the area of the rectangle has increased by 65%.
5.
In a village, 18% of the population is children and 10% of the children are female. If the number of female children is 90, then what is the population?
Correct Answer
A. 5000
Explanation
If 10% of the children are female and the number of female children is 90, then the total number of children in the village can be calculated by dividing 90 by 10% (0.10). This gives us 900 children in total.
Given that 18% of the population is children, we can find the total population by dividing the number of children (900) by 18% (0.18).
Therefore, the population of the village is 5000.
6.
If the radius of a circular region were decreased by 30 percent, the area of the circular region would decrease by what percent?
Correct Answer
D. 51
Explanation
When the radius of a circular region is decreased by 30 percent, the new radius becomes 70 percent (100 percent minus 30 percent) of the original radius. The area of a circle is calculated by multiplying π (pi) by the square of the radius. Therefore, if the radius is decreased by 30 percent, the new area would be 0.7^2 (0.49) times the original area. To find the percentage decrease in area, we subtract this value from 1 (100 percent) and multiply by 100. Therefore, the area of the circular region would decrease by 51 percent.
7.
30% of the students in a class wear shoes, 20% of the students, who wear shoes, wear Nike shoes. If the class has 300 students then how many wear Nike shoes?
Correct Answer
C. 18
Explanation
If 30% of the students in the class wear shoes, then the number of students who wear shoes is 30% of 300, which is 0.3 * 300 = 90.
Out of these 90 students, 20% wear Nike shoes. Therefore, the number of students who wear Nike shoes is 20% of 90, which is 0.2 * 90 = 18.
8.
Peter got 30%, of the maximum marks in an examination and failed by 10 marks. However, Paul who took the same examination got 40% of the total marks and got 15 marks more than the passing marks. What was the passing marks in the examination?
Correct Answer
C. 250
Explanation
Peter got 30% of the maximum marks and failed by 10 marks. This means that if he had scored 100% (maximum marks), he would have passed by 10/0.3 = 33.33 marks. Therefore, the passing marks would be 100 - 33.33 = 66.67% of the maximum marks.
Paul got 40% of the total marks and got 15 marks more than the passing marks. This means that if he had scored 100% (total marks), he would have scored 66.67 + 15 = 81.67 marks.
Since Peter failed by 10 marks and Paul got 81.67 marks, the passing marks would be 81.67 - 10 = 71.67% of the total marks.
To find the passing marks in the examination, we need to calculate 71.67% of the total marks.
Therefore, the passing marks in the examination is 71.67% of the total marks, which is equal to 250.
9.
Rajan got an increment of 25 % on his salary at the start of the year 2007. But 2008 is a recession year the company cut the salaries of all employees by 10% by the end of the year. What were the net percentage change in his compared to 2006 end and 2009 start?
Correct Answer
C. 12.5
Explanation
Rajan received a 25% increment on his salary in 2007. However, in 2008, during the recession, the company reduced the salaries of all employees by 10%. To calculate the net percentage change in his salary compared to the end of 2006 and the start of 2009, we need to consider the cumulative effect of both the increment and the salary cut.
First, we calculate the increase in salary in 2007: 25% of the salary at the end of 2006.
Next, we calculate the decrease in salary in 2008: 10% of the increased salary in 2007.
Finally, to find the net percentage change, we subtract the decrease in salary from the increase in salary and express it as a percentage of the salary at the end of 2006. The net percentage change is 12.5%.
10.
Milk contains 80% water and 20% solid. If 50% of the water is evaporated from milk after boiling it for 15 mins, then what will be the percentage solid in the boiled milk?
Correct Answer
B. 33.33 %
Explanation
When milk is boiled, 50% of the water evaporates, which means that only 50% of the original water content remains. Since the milk initially contains 80% water and 20% solids, after boiling, the percentage of solids remains the same at 20%. Therefore, the percentage of solids in the boiled milk is 20% of the remaining 50% water, which equals 10%. To find the overall percentage of solids in the boiled milk, we divide the percentage of solids by the total volume of the milk, which is 100%. So, the percentage of solids in the boiled milk is 10% divided by 100%, which equals 0.1 or 10%. Converted to a percentage, it is 33.33%.