An industrial loom weaves 0.128 metres of cloth every second. Approximately, how many seconds will it take for the loom to weave 25 metre of cloth ?

Answer: Option B

Explanation:

Let the time required by x seconds.
Then, More cloth means More time (Direct Proportion)
So,
\begin{aligned}
0.128 : 1 :: 25 : x
=> x = \frac{25*1}{0.128} \\
=> x = 195.31
\end{aligned}

So time will be approx 195 seconds

Answer: Option B

Explanation:

Less Cows, More days (Indirect Proportion)
Less bags, Less days (Direct Proportion)

\begin{aligned}
\begin{bmatrix}Cows & 1 & 40 \\Bags & 40 & 1 \end{bmatrix} :: 40 : x \\
=> x * 40 * 1= 40 * 1 * 40 \\
=> x = 40
\end{aligned}

Answer: Option C

Explanation:

Please always remember, that what exactly we need to calculate before applying chain formula. As in this question we need to find how many mats, RIGHT !
So we will compare everything with "number of mats"
As,

More men, More number of mats (Direct Proportion)
More days, More number of mats (Direct Proportion)

So, it can be solved as,

\begin{aligned}
\begin{bmatrix}Weavers & 4 & 8 \\Days & 4 & 8 \end{bmatrix} :: 4 : x \\

=> x*4*4 = 8*8*4 \\
=> x = 16
\end{aligned}

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 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.