Answer

Verified

413.7k+ views

**Hint**: The diameter of the well is 150cm, so the diameter of the inner circle is 150cm. So, the inner radius is equal to 75cm, i.e., half of the inner diameter. Also, the length of the outer edge of the parapet is 660cm, i.e., the circumference of the outer circle is 660cm. We know that the circumference of the circle is given by $ 2\pi \left( radius \right) $ , so use this formula to get the outer radius. Finally find the difference between the inner and outer radius to get the answer.

**:**

__Complete step-by-step answer__To start with the question let us draw the diagram of the park with the road along its boundary for better visualisation.

As it is given that the diameter of the well is 150cm, so the diameter of the inner circle is 150cm. So, the inner radius is equal to 75cm, i.e., half of the inner diameter.

$ \therefore r=75cm $

Also, it is given that the length of the outer edge of the parapet is 660cm, i.e., the circumference of the outer circle is 660cm and we know that the circumference of the circle is given by $ 2\pi R $ .

$ \begin{align}

& \therefore 2\pi R=660 \\

& \Rightarrow R=\dfrac{660}{2\pi } \\

\end{align} $

Now, if we put $ \pi =\dfrac{22}{7} $ , we get

$ R=\dfrac{660\times 7}{2\times 22}=105cm $

Now, the width of the parapet is the difference of the outer and inner radius. So, the width of the parapet is:

$ R-r=105-75=30cm $

**So, the correct answer is “Option A”.**

**Note**: The key to this question is to draw the correct diagram of the situation given in the question, as once you have drawn the diagram, we just have to put the formula of circumference of circle and find the difference of the two radii to get the answer. Also, be careful about the calculation part as there is a high chance of making a mistake in the calculation part.

Recently Updated Pages

How do you evaluate cos left dfrac13pi 12 right class 10 maths CBSE

How do you rewrite the inequality left 11 2x right class 10 maths CBSE

How do you solve 4 3x 025 class 10 maths CBSE

How do you find the zeros of x3 3x2 + 6x 18 class 10 maths CBSE

Consider the following statements in respect of the class 10 maths CBSE

How do you factor 2x3 + 3x2 8x 12 class 10 maths CBSE

Trending doubts

Difference Between Plant Cell and Animal Cell

Give 10 examples for herbs , shrubs , climbers , creepers

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

Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE

Write a letter to the principal requesting him to grant class 10 english CBSE

Change the following sentences into negative and interrogative class 10 english CBSE

Write the 6 fundamental rights of India and explain in detail

Name 10 Living and Non living things class 9 biology CBSE

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