Question

Drops of water fall at a uniform rate from a Kalash (pot) over the Shivling in the Shiva temple. If 9 drops fall in 10 sec, how many drops fall in 15 sec?
(a) 14
(b) 12
(c) 13
(d) 16

Answer 1

Hint: Here, the uniform rate is given so we can use simple methods of proportion to solve this problem. Use the fact that if two things are in direct proportion, then the rate of increasing or decreasing of one is the same as the rate of increasing or decreasing of the other.

Complete Step-by-step Solution
Given that
 9 drops take 10 seconds time to fall from the pot over Shivling in the Shiva temple.

We can calculate the time of one drop by dividing the time $10\;{\rm{s}}$ with the number of drops that is $9$.
$\begin{array}{l}
 = \dfrac{{10}}{9}\\
 = 1.111
\end{array}$
Now, we know that one drop will take approximately \[1.111\;{\rm{s}}\] to fall.
Also, two drops will take approximately \[2.222\;{\rm{s}}\]to fall.

Similarly, 10 drops will take approximately \[11.11\;{\rm{s}}\]to fall.
11 drops will take approximately \[1.222\;{\rm{s}}\] to fall.
12 drops will take approximately \[13.332\;{\rm{s}}\] to fall.
13 drops will take approximately \[14.443\;{\rm{s}}\] to fall.
14 drops will take approximately \[15.554\;{\rm{s}}\]to fall.

Now, this time surpasses the given time. So, 13 drops will fall in 15 seconds.

Therefore, the correct answer is option (c).

Note: Here, we have calculated the amount of drops that fall in 15 seconds by unitary method. First calculate the time consumed for one drop, then we will multiply the value of time by 15 to determine the drops fall in 15 seconds. We can use alternate method to solve this problem which is,
Drops falling in time 10 seconds is 9.
So, Drops falling in 1 second is 0.9.
Drops falling in time 15 seconds is 13.5.