Question

What is 15 % of 10 % of 20 % of 1000?
(a). 1.50
(b). 67
(c). 150
(d). 3

Answer 1

Hint: Recall the formula for percentage, that is, Percentage = \[\dfrac{{{\text{Required value}}}}{{{\text{Total value}}}} \times 100\% \]. Then, calculate step by step, starting from 20 % of 1000, then 10 % of the result, then 15 % of this result to obtain the answer.

Complete step-by-step answer:
The percentage of a quantity means a fraction of the quantity expressed by taking a hundred as a whole. 100 % means the entire quantity or the whole. The word percent comes from the Latin word “Per Cent” where Centum means a hundred.
The percentage is just a convenient way to express a fraction with the hundred as a whole.
A percentage is a number expressed as a fraction of 100. It is calculated by multiplying the numerical value of the ratio by 100.
To calculate the value of the percentage of some number, we need to multiply that number with the required percentage and divide by 100.
We need to calculate 15 % of 10 % of 20 % of 1000. First, we calculate 20 % of 1000, which is 20 multiplied with 1000 divided by 100.
20% of 1000 = \[\dfrac{{20 \times 1000}}{{100}}\]
20% of 1000 = 200........(1)
Next, we need to calculate 10 % of 20 % of 1000, which from equation (1) is 10 % of 200. 10 % of 200 is calculated by multiplying 10 with 200 and dividing by 100.
10% of 200 = \[\dfrac{{10 \times 200}}{{100}}\]
10% of 200 = 20...........(2)
Next, we need to calculate 15 % of 10 % of 20 % of 1000, which from equation (2) is 15 % of 20. 15 % of 20 is calculated by multiplying 15 with 20 and dividing by 100.
15% of 20 = \[\dfrac{{15 \times 20}}{{100}}\]
15% of 20 = 3
Hence, 15 % of 10 % of 20 % of 1000 is 3.
Hence, option (d) is the correct answer.

Note: Note that 15 % of 10 % of 20 % of 1000 is the same as 10 % of 15 % of 20 % of 1000, the order in which you take the percentage does not matter as long as you are concerned only with the final answer.