1. Raman's salary was decreased by 50% and subsequently increased by 50%. How much percent does he loss.
75
65
45
25
Answer: Option D
Explanation:
Let the origianl salary = Rs. 100
It will be 150% of (50% of 100)
= (150/100) * (50/100) * 100 = 75
So New salary is 75, It means his loss is 25%
2. Teacher took exam for English, 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 calcualte average marks of the remaining students of the class.
60
70
75
80
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.
3. Two numbers are less than third number by 30% and 37% respectively. How much percent is the second number less than by the first
8%
9%
10%
11%
Answer: Option C
Explanation:
Let the third number is x.
then first number = (100-30)% of x
= 70% of x = 7x/10
Second number is (63x/100)
Difference = 7x/10 - 63x/100 = 7x/10
So required percentage is, difference is what percent of first number
=> (7x/100 * 10/7x * 100 )% = 10%
4. A student multiplied a number by 3/5 instead of 5/3. What is the percentage error.
64%
65%
66%
67%
Answer: Option A
Explanation:
Let the number be x,
then,
\begin{aligned}
\frac{5}{3} - \frac{3}{5} = \frac{16}{15}x
\end{aligned}