Question

*→* A circle field of diameter 42 m needs to be cleaned. if the cost of cleaning the field is Rs. 2.35 per m², find the cost of cleaning the field?​

Answer 1

${\orange{\bigstar}} \ {\underline{\green{\textsf{\textbf{Given :-}}}}}$

Diameter of the circle = 42 m

Cost of cleaning per m² = ₹2.35

${\blue{\bigstar}} \ {\underline{\pink{\textsf{\textbf{To Find :-}}}}}$

Cost of cleaning the whole field

${\red{\bigstar}} \ {\underline{\purple{\textsf{\textbf{Formula Used :-}}}}}$

${\boxed{\green{\textsf{\textbf{Area of a circle = }}} {\blue{\sf{\pi r^2}}}}}$

where,

r = Radius

${\sf{\pi = \dfrac{22}{7}}}$

${\orange{\bigstar}} \ {\underline{\blue{\textsf{\textbf{Solution :-}}}}}$

$Radius = {\sf{\dfrac{Diameter}{2}}}$

$\longmapsto {\sf{\dfrac{42}{2}}}$

$\longmapsto {\sf{21 \ m}}$

${\pink{\textsf{\textbf{Radius = 21 m}}}}$

According to the question by using the formula of Area of a Circle, we get,

$\dashrightarrow \ {\green{\sf{Area \ of \ circular \ field = (\pi \times 21^2) \ m^2}}}$

Solving the above equation,

$: \ \Longrightarrow \ {\sf{ \bigg ( \dfrac{22}{7} \times 21^2 \bigg ) \ m^2}}$

$: \ \Longrightarrow \ {\sf{ \bigg ( \dfrac{22}{7} \times 21 \times 21 \bigg ) \ m^2}}$

$: \ \Longrightarrow \ {\sf{ \bigg ( \dfrac{22}{7} \times 441 \bigg ) \ m^2}}$

$: \ \Longrightarrow \ {\sf{ \bigg ( \dfrac{22}{{\cancel{7}}^{ \ 1}} \times {\cancel{441}}^{ \ 63} \bigg ) \ m^2}}$

$: \ \Longrightarrow \ {\sf{(22 \times 63) \ m^2}}$

$: \ \Longrightarrow \ {\sf{1,386 \ m^2}}$

${\blue{\textsf{\textbf{Area of the circular field = 1,386 sq. m.}}}}$

Cost of cleaning the field = ₹ (1,386 × 2.35)

$: \ \Longrightarrow \ {\sf{\purple{Rs. \ 3257.1}}}$

${\boxed{\orange{\textsf{\textbf{Cost of cleaning the field is Rs. 3257.1}}}}}$

Answer 2

Answer:

A circle field diameter of 42 m

where radius is = r

pi = 22/7

solution

Radius = diameter/ 2

Radius = 42 / 2

Radius = 21

Area of the circle field

22/7 × 21 ×21

= 22×3×21

= 1386 m

the cost of cleaning the field is 2.35 Rs

= Area of circle field X cost of cleaning the field

1386 × 2.35

= 3257.1 per metre. sq

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