Question Detail

In a college, the ratio of the number of boys to girls is 8 : 5. If there are 200 girls, the total number of students in the college is

Answer: Option B

Explanation:

Let the boy are 8x and Girls are 5x

=> 5x = 200
=> x = 40

Total students = 8x+5x = 13x = 13(40) = 520

1. In a mixture 60 litres, the ratio of milk and water 2 : 1. If the this ratio is to be 1 : 2, then the quanity of water to be further added is

20 liters
30 liters
50 liters
60 liters

Answer: Option D

Explanation:

Quantity of Milk = 60*(2/3) = 40 liters
Quantity of water = 60-40 = 20 liters

As per question we need to add water to get quantity 2:1

=> 40/(20+x) = 1/2
=> 20 + x = 80
=> x = 60 liters

2. A and B together have Rs. 1210. If 4/15 of A's amount is equal to 2/5 of B's amount. How much amount B have.

Rs 484
Rs. 480
Rs 478
Rs 470

Answer: Option A

Explanation:

In this type of question, we will first try to calculate the ratio of two persons. Once we get ratio then we can easily get our answer. So lets solve this.

\begin{aligned}
\frac{4}{15}A = \frac{2}{5}B \\
A = \left(\frac{2}{5}*\frac{14}{4}\right)B \\
A = \frac{3}{2}B \\
\frac{A}{B} = \frac{3}{2} \\
A:B = 3:2 \\
\text{B's Share = }\frac{2}{5}*1210 = 484
\end{aligned}

3. Rs. 120 are divided among A, B, C such that A's share is Rs. 20 more than B's and Rs. 20 less than C's. What is B's share

Rs 10
Rs 20
Rs 24
Rs 28

Answer: Option B

Explanation:

Let C = x. Then A = (x—20) and B = (x—40).
x + x - 20 + x - 40 = 120 Or x=60.
A:B:C = 40:20:60 = 2:1 :3.
B's share = Rs. 120*(1/6) = Rs. 20

4. Salaries of Ravi and Sumit are in the ratio 2:3. If the salary of each is increased by Rs 4000, the new ratio becomes 40:57. What is Sumit present salary.

32000
34000
38000
40000

Answer: Option C

Explanation:

Let the original Salaries of Ravi and Sumit is 2x and 3x.

So as per question

\begin{aligned}
\frac{2x+4000}{3x+4000} = \frac{40}{57} \\
=> 57(2x+4000) = 40(3x+4000) \\
=> 6x = 68000 \\
=> 3x = 34000 \\

\text{ Sumit Salary =} 3x+4000 \\
34000 + 4000 = 38000

\end{aligned}

5. There are two numbers and their ratio is 3 : 9. If we substract 9 from both numbers then their ratio becomes 12 : 13, what is value is smaller number ?

Answer: Option D

Explanation:

From question, lets assume that two numbers are 3x and 5x.

\begin{aligned}
\text{then, }\frac{3x - 9}{ 5x - 9} = \frac{12}{23}\\
=> \text{23(3x - 9) = 12(5x - 9)}\\
=> 9x = 99 \\
=> x = 11
\end{aligned}
So numbers are 3(11) = 33, 5(11) = 55.
Smaller number is 33.