Question Detail

If 40% of a number is equal to two-third of another number, what is the ratio of first number to the second number.

Answer: Option D

Explanation:

Let the first number is A and second number is B.

As per question

\begin{aligned}
\frac{40}{100}A = \frac{2}{3}B \\

\frac{A}{B} = \frac{2}{3}*\frac{100}{40} \\
\frac{A}{B} = \frac{5}{3} \\
=> A:B = 5:3

\end{aligned}

1. If A:B = 2:3, B:C = 4:5 and C:D = 6:7, then find the value of A:B:C:D

15:24:30:35
16:24:30:35
17:24:30:35
18:24:30:35

Answer: Option B

Explanation:

\begin{aligned}
A:B = 2:3 \\
B:C = 4:5 = (4*\frac{3}{4} : 5*\frac{3}{4}) \\
= 3:\frac{15}{4} \\
C:D = 6:7 = (6*\frac{15}{24} : 7*\frac{15}{24}) \\
= \frac{15}{4}:\frac{35}{8} \\
A:B:C:D = 2:3:\frac{15}{4}:\frac{35}{8} \\
= 16:24:30:35
= 8:12:9
\end{aligned}

2. 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

3. The sum of three numbers is 98. If the ratio of the first to the second is 2:3 and that of the second to the third is 5:8, then the second number is

Answer: Option D

Explanation:

\begin{aligned}
a:b = 2:3 \\
b:c = 5:8 = (5*\frac{3}{5} : 8*\frac{3}{5}) \\
= 3:\frac{24}{5} \\
a:b:c = 2:3:\frac{24}{5} \\
= 10:15:24 \\
b = 98*\frac{15}{49} \\
= 30
\end{aligned}

4. The salaries of A, B and C are of ratio 2:3:5. If the increments of 15%, 10% and 20% are done to their respective salaries, then find the new ratio of their salaries.

20:33:60
21:33:60
22:33:60
23:33:60

Answer: Option D

Explanation:

Let A salary be 2k
B salary be 3k and C salary be 5k

\begin{aligned}
\text{A's new salary = }\frac{115}{100}*2k \\
= \frac{23}{10}k \\
\text{B's new salary = }\frac{110}{100}*3k \\
= \frac{33}{10}k \\
\text{C's new salary = }\frac{120}{100}*5k \\
= 6k \\

\text{New ratio = }\\
\frac{23k}{10}:\frac{33k}{10}:6k \\
= 23:33:60 \\
\end{aligned}

5. If a:b = 2:3 and b:c = 4:3, then find a:b:c

8:12:9
2:3:8
2:3:9
2:3:12

Answer: Option A

Explanation:

\begin{aligned}
a:b = 2:3 \\
b:c = 4:3 = (4*\frac{3}{4} : 3*\frac{3}{4}) \\
= 3:\frac{9}{4} \\
a:b:c = 2:3:\frac{9}{4} \\
= 8:12:9
\end{aligned}