Question Detail

If 2 : 9 :: x : 18, then find the value of x

Answer: Option C

Explanation:

Treat 2:9 as 2/9 and x:18 as x/18, treat :: as =

So we get 2/9 = x/18
=> 9x = 36
=> x = 4

1. A dog takes 3 leaps for every 5 leaps of a hare. If one leap of the dog is equal to 3 leaps of the hare, the ratio of the speed of the dog to that of the hare is

Answer: Option B

Explanation:

Dog : Hare = (3*3) leaps of hare : 5 leaps of hare
= 9 : 5

2. The least whole number which when subtracted from both the terms of the ratio 6 : 7 to give a ratio less than 16 : 21, is

Answer: Option A

Explanation:

Let x is subtracted.
Then,
\begin{aligned}
\frac{(6-x)}{(7-x)}< \frac{16}{21} \\

21(6—x) < 16(7—x)\\
=> 5x > 14 = x > 2.8
\end{aligned}

Least such number is 3

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. 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}

5. 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}