NCERT Solutions Class 7 Mathematics Solutions for Exercise 11.1 in Chapter 11 - Perimeter and Area

Question 13 Exercise 11.1

Q8) A door of length 2 m and breadth 1m is fitted in a wall. The length of the wall is 4.5 m and the breadth is 3.6 m. Find the cost of white washing the wall, if the rate of white washing the wall is Rs 20 per m^2



Length of wall= 4.5m

Breadth of the wall= 3.6m

Length of the door =2m

Breadth of the door= 1m

Area of the wall = l\times b=4.5m\times3.6m=\ 16.20m^2

Area of the door = l\times b=2m\times1m=2m^2

Therefore area of the wall to be white washed= Area of the wall - Area of the door

=Rs\ 14.20\times20=Rs\ 284.00

Hence, the required area= 14.20m^2 and the required cost= Rs 284

Video transcript
"Base welcome to lead over the door of length 2 meter and 1 we respected in the Box the length of the wall. This part is 4.5 liter and the breadth of the wall is 3.6 liter find the cost of whitewash in the bowl of the rate of iPods in the wall is rupees 20 per meter Square. First of all, let's calculate the area of the world competing each of the wall, which will be equal to 4 point 5 into 3 point 6 4 4 point 5 into 3 .6 + area of a rectangle is length into breadth. This will give the area of the water to be 16 point 16 point. All right. So this is the complete one. Now first. There's a do now when we have eight watching or when you're painting to do not in the do neither do they spin it separate. So what we'll do is we'll subtract the area of the dough. So the area of the door will be 2 into 1. Okay, because the length is 200 the sons of 2 into 1 2. 2 into 1 which will be equal to 2 meter Square therefore the area that is to be my first is equal to sixteen point two zero minus two meters which will be equal to fourteen point two zero meters, right? This is the total area that is to be white cross. Now. The price of whitewashing is a bitch 20 per meter Square. So there is total 14.2 so will be multiplied by 20 the answer my dear generally come out to be 2828. Wait until 200. I'm sorry. Sorry, sorry 284 poopies. Right. So thank you so much guys for watching the video. "
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