Answer

Verified

435.9k+ views

**Hint:**Here, we have to find the value of forty percent of an unknown number. So first of all suppose the number is $x$ then calculate its three sevenths, then one third and then two fifths of the previous number and this number is equal to $15$. And after solving the equation we get the number and then find its forty percent.

**Complete step-by-step solution:**

Here, we have to calculate forty percent of a number.

Let the required number be $x$.

Three seventh of the number $x = \dfrac{3}{7}x$.

Now, one- third of the number $\dfrac{3}{7}x = \dfrac{1}{3} \times \dfrac{3}{7}x = \dfrac{1}{7}x$.

Now, two- fifth of the number $\dfrac{1}{7}x = \dfrac{2}{5} \times \dfrac{1}{7}x$.

Here, it is given that two- fifth of one- third of one- seventh of number $x$ is $15$.

So, $\dfrac{2}{{35}}x = 15$

$ \Rightarrow x = \dfrac{{15 \times 35}}{2}$

$\therefore x = \dfrac{{525}}{2}$

Thus, the required number is $\dfrac{{525}}{2}$.

Now, we have to calculate the forty percent of the number we got above.

So, forty percent of $\dfrac{{525}}{2}$.

$ = 40\% $of $\dfrac{{525}}{2}$.

$ = \dfrac{{40}}{{100}} \times \dfrac{{525}}{2}$.

$ = 105$.

Thus, forty percent of the required number is $105$.

**Hence, option (C) is the correct answer for this question.**

**Note:**The most crucial point where we have to give special care is when we are writing equations.

Suppose the number and proceed according to the given statement and finally equates it with the given numerical value.

Percent means a part in every hundred. $x\% $ means $x$ parts in a total of hundred parts. Mathematically it is written as $\dfrac{x}{{100}}$.

Recently Updated Pages

what is the correct chronological order of the following class 10 social science CBSE

Which of the following was not the actual cause for class 10 social science CBSE

Which of the following statements is not correct A class 10 social science CBSE

Which of the following leaders was not present in the class 10 social science CBSE

Garampani Sanctuary is located at A Diphu Assam B Gangtok class 10 social science CBSE

Which one of the following places is not covered by class 10 social science CBSE

Trending doubts

Which are the Top 10 Largest Countries of the World?

How do you graph the function fx 4x class 9 maths CBSE

The Equation xxx + 2 is Satisfied when x is Equal to Class 10 Maths

Fill the blanks with the suitable prepositions 1 The class 9 english CBSE

In Indian rupees 1 trillion is equal to how many c class 8 maths CBSE

Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE

One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE

Why is there a time difference of about 5 hours between class 10 social science CBSE

Give 10 examples for herbs , shrubs , climbers , creepers