Question

A glass was filled with 10 ounce of water, and 0.01 ounce of the water evaporated each day during a 20-day period. What of the original amount of water evaporated during this period?
$\left( A \right)$0.002%
$\left( B \right)$ 0.02%
$\left( C \right)$ 0.2%
$\left( D \right)$ 2%
$\left( E \right)$ 20%

Answer 1

Hint – In this particular question use the concept that if 0.01 ounce of water is evaporated per day in a 20 day period than in 20 days the ounce of water is evaporated is the multiplication of the 20 day period and the amount of water evaporated in 1 day so use this concept to reach the solution of the question.

Complete step-by-step answer:
Given data:
A glass was filled with 10 ounce of water.
And 0.01 ounce of the water evaporated each day during a 20 day period.
Now we have to calculate what percentage of the original amount of water evaporated during this interval.
Now 0.01 ounce of water evaporated in 1 day.
So in a 20 day period the amount of water evaporated is the multiplication of the 20 day period and the amount of water evaporated in 1 day.
 So in a 20 day period the amount of water is evaporated = (20 $ \times $ 0.01) = 0.2 ounce of water.
So in a 20 day period 0.2 ounce of water is evaporated.
Now the percentage of the water evaporated is the ratio of the water evaporated in a 20 day period to the original amount of water multiplied by 100.
Therefore, percentage of the original amount of water evaporated during this period = $\dfrac{{0.2}}{{10}} \times 100$
Now simplify this we have,
Therefore, percentage of the original amount of water evaporated during this period = 0.2(10) = 2%
So 2% of the original amount of water evaporated during this period.
So this is the required answer.
Hence option (D) is the correct answer.

Note – Whenever we face such types of questions the key concept we have to remember is that the percentage of the water is evaporated is the ratio of the water evaporated in 20 day period to the original amount of water multiplied by 100, so first find out the evaporated water in 20 day period as above then substitute this value in the percentage formula as above and simplify we will get the required answer.