If the price of 23 toys is 276, then what will the price of 12 toys ?

Answer: Option A

Explanation:

Less Men, means more Days {Indirect Proportion}

Let the number of days be x
then,

27 : 36 :: 18 : x
[Please pay attention, we have written 27 : 36 rather than 36 : 27, in indirect proportion, if you get it then chain rule is clear to you :)]

\begin{aligned}
x = \frac{36*18}{27} \\
x = 24
\end{aligned}
So 24 days will be required to get work done by 27 men.

Answer: Option D

Explanation:

Quarter of Kg means 250 gm

Less weight, less price (Direct Proportion)
So,
\begin{aligned}
250:200 :: 60:x \\
=> x = \frac{200*60}{250} \\
=> x = 48
\end{aligned}

So 200 gm will cost 48 paise.

Answer: Option C

Explanation:

As it is given that food is there for 54 days for 2000 students,
But after 15 days, remaining food was sufficient for 2000 students for 39 days only ( as 54-15 = 39 )
Let x number of students came in hostel after 15 days,
=> Total number of students after 15 days = 2000 + x
=> Remaining food was enough for (2000 + x) students for 20 days
So here is indirect proportion, as more people and less food
=> 2000 : ( 2000 + x ) :: 20 : 39
=> 2000 * 39 = ( 2000 + x ) * 20
=> 3900 = 2000 + x
=> x = 3900 - 2000
=> x = 1900

Answer: Option B

Explanation:

Less shadow, Less Height (Direct Proportion)
So, let height of building be x metre
then,
\begin{aligned}
40.25 : 17.5 :: 28.75 : x \\

=> x = \frac{17.5*28.75}{40.25} \\
=> x = 12.5
\end{aligned}

So height of building should be 12.5 metre

Answer: Option A

Explanation:

Less toys, Less Price (Direct Proportion)
So, let the price be Rs. x
then,
\begin{aligned}
23:12 :: 276:x
=> x = \frac{276*12}{23} \\
=> x = 144
\end{aligned}

So price of 12 toys will be Rs. 144