Question

A blackboard of sides $4m$ $50cm$ and $3m$ $20cm$ is to be painted. Find the cost of painting at the rate of $Rs25$ per square metre.

Answer 1

Step-by-step explanation:

It is given that the measures of sides of blackboard are 4 m 50 cm and 3m 20 cm, the larger side should be the length of the blackboard, and the smaller side should be the breadth of the blackboard.

Therefore,

Length of the blackboard = 4m 50 cm

⇒ 4m + 50 cm

⇒ 4m + ( 50 / 100 ) m

⇒ 4m + 0.5 m

⇒ 4.5 m

Breadth of the blackboard = 3m 20 cm

⇒ 3m + 20 cm

⇒ 3m + ( 20 / 100 )m

⇒ 3m + 0.2 m

⇒ 3.2 m

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From the properties of a rectangle, we know : -

Area of rectangle = length x breadth

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Thus,

= > Area of blackboard = 4.5 m x 3.2 m

= > Area of blackboard = 14.4 m²

Therefore,

⇒ Cost of painting = rate of painting x area to be painted

= > Cost of painting = Rs 25 / m² x 14.4 m²

= > Cost of painting = Rs 25 x 14.4

= > Cost of painting = Rs 360