Question

a blackboard of sides for 4m 50 cm and 3 M 20 cm is to be painted find the cost of painting at the rate rs 25 per square metre

Answer 1

Answer:

Cost of painting the blackboard at the rate of Rs 25 per sq metre is Rs 360 .

Step-by-step explanation:

It is given that the measures of sides of blackboard are 4 cm 50 cm and 3m 20 cm, larger side should be the length of the blackboard, and 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 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 m^2

Therefore,

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

= > Cost of painting = Rs 25 / m^2 x 14.4 m^2

= > Cost of painting = Rs 25 x 14.4

= > Cost of painting = Rs 360

Hence,

Cost of painting the blackboard at the rate of Rs 25 per sq metre is Rs 360 .