Question

A black board is 17dm 7cm long and 11dm 5cm broad. What will be the cost of painting it at the rate of 35 paise per square centimetre?​

Answer 1

Answer:

Rs. 712425

Step-by-step explanation:

A black board is 17 dm 7 cm long and 11 dm 5 cm broad.

Here..

• Length of board = 17 × 10 + 7

= 170 + 7

= 177 cm

• Breadth of board = 11 × 10 + 5

= 110 + 5

= 115 cm

Now,

Area of blackboard = Area of rectangle

Area of rectangle = length × breadth

Substitute the known values in above formula

=> 177 × 115

=> 20355 cm²

Now,

Cost of painting the blackboard at the rate of 35 paise per cm²

=> 20355 × 35

=> Rs. 712425

Answer 2

$\bold{\underline{\underline{Answer:}}}$

Cost of painting = ₹ 7,12,425 .

$\bold{\underline{\underline{Step\:-\:by\:-\:step\:explanation:}}}$

Given :

• Length of the black board is 17 dm 7 cm
• Breadth of the black board is 11 dm 5 cm
• Cost of painting the blackboard is 35 paise per square centimeter.

To find :

• Cost of painting the blackboard.

Solution :

Since the values are given in decimetre, we will first convert the units.

For length :-

1 dm = 10 cm

•°• 17 dm = 17(10) = 170 cm

Length of the blackboard = 170 + 7

•°• Length (l) = 177 cm

For breadth :-

$\rightarrow$ $\bold{Breadth=11(10)}$

$\rightarrow$ $\bold{Breadth=110}$

•°• Breadth(b) = 110 + 5 = 115 cm

So now we have the length and breadth of the black board in same unit. So let's find the area of the blackboard.

Area of blackboard :-

$\rightarrow$$\bold{Area\:=\:length\times\:breadth}$

Block in the values,

$\rightarrow$ $\bold{Area\:=\:177\times\:115}$

$\rightarrow$ $\bold{Area\:=20355}$

•°• Area = 20355 cm²

Now, to find the cost.

Cost required will be area of the blackboard times cost of painting the blackboard per square centimeter.

Cost of painting,

$\bold{Area\:of\:blackboard\times\:rate\:per\:square\:centimeter}$

$\rightarrow$ $\bold{20355\times\:35}$

$\rightarrow$ $\bold{712425}$

•°• Cost of painting the blackboard at the rate of 35 paise per square centimeter is ₹ 7, 12, 425.