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 C

Answer: Option C

Explanation:

More Men, Less Hours {Indirect Proportion}
Less Days, More Hours {Indirect Proportion}
\begin{aligned}
\begin{bmatrix}Men & 15 & 10 \\Days & 12 & 18 \end{bmatrix} :: 6 : x \\
=> x * 15 * 12 = 10 * 18 * 6 \\
=> x = \frac{10*18*6}{15*12} \\
=> x = 6
\end{aligned}

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 C

Explanation:

Although we can first calculate the cost of one toy and then can multiply it with 40 to get the result.
but we will solve it with chain rule so that we can prepare ourself for other complex problems which we can solve easily by applying this rule.

Let the required cost be Rs. x
More toys means More Cost. (Direct Proportion)

\begin{aligned}
15:40 :: 240:x \\
=> x = \frac{240*40}{15} \\
=> x = 640
\end{aligned}

So 40 toys will cost Rs 640

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