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surface area of a room watch

1. Hi guys,
I'm struggling in question below if anyone can give me a hint would be perfect.
A room has dimensions 6.8 metres x 9.2 metres x 2.5 metres. Stephanie wants to paint the walls of the room,. A large tin of paint covers 20m^2 and costs 11.75. Ignoring windows and doors and allowing for two coats of paint, how much will it cost Stephanie to paint the room?
so basically what i've done was calculating the area surface of the room and divide it by 20 to find out how many tins of paint we need to paint the room and then multiply that by 11.75 which gives me a wrong answer.

(Also note the 2 coats, and allow for the fact that the answer may take into account that you can only buy full tins of paint. So if you calculate you need 4.5 tins of paint (for example), then you actually need to buy 5 tins).
3. (Original post by DFranklin)

(Also note the 2 coats, and allow for the fact that the answer may take into account that you can only buy full tins of paint. So if you calculate you need 4.5 tins of paint (for example), then you actually need to buy 5 tins).
What does actually mean 2 coats of paint??
4. (Original post by Alen.m)
What does actually mean 2 coats of paint??
It means everything gets painted twice. (You have obviously never painted a room!)
5. (Original post by DFranklin)
It means everything gets painted twice. (You have obviously never painted a room!)
Yeah never needed to! So basically you devided the totall area surface of the room by 20 to find out how many tin of paint you need to cover the whole room?
6. Again, you need to allow for painting it twice...
7. (Original post by DFranklin)
Again, you need to allow for painting it twice...
How would you explain that mathematically? Like the number of tins need to be devided or multiplied by 2?
8. (Original post by Alen.m)
Yeah never needed to! So basically you devided the totall area surface of the room by 20 to find out how many tin of paint you need to cover the whole room?
I think the question refers to painting the walls, whereas you have included the walls, floor and ceiling...
9. (Original post by Alen.m)
How would you explain that mathematically? Like the number of tins need to be devided or multiplied by 2?
1) Determine the surface area to be painted;

2) Work out how much paint is needed for one coat of the area from (1), based on the given coverage information for the paint;

3) Multiply by 2 to give the amount of paint needed for two coats;

4) Divide by the amount of paint contained by one tin, to determine how many tins of paint are needed;

5) If the answer to (4) is not an integer, round it up t the next integer.
10. (Original post by old_engineer)
1) Determine the surface area to be painted;

2) Work out how much paint is needed for one coat of the area from (1), based on the given coverage information for the paint;

3) Multiply by 2 to give the amount of paint needed for two coats;

4) Divide by the amount of paint contained by one tin, to determine how many tins of paint are needed;

5) If the answer to (4) is not an integer, round it up t the next integer.
I've ignored the celling and floor as you've suggested but the answer still not correct
11. It would help if you didn't paint the floor and ceiling and got the room dimension right. It is 9.8m long, not 9.2m.
12. (Original post by Good bloke)
It would help if you didn't paint the floor and ceiling and got the room dimension right. It is 9.8m long, not 9.2m.
It's actually 9.2m...
13. (Original post by Alen.m)
It's actually 9.2m...
In your OP you wrote 9.8, not 9.2.
14. (Original post by Alen.m)
It's actually 9.2m.
You told us, in the OP, that it is 9.8m.
15. (Original post by Good bloke)
You told us, in the OP, that it is 9.8m.
yeah my bad ... i'll edit it now . it shouldn't be that complicated as it's only a grade C question. I don't know why i cant get it right tho
16. I suspect you cannot do multiplication very well the answer is 8 cans exactly, though I see your picture shows you are painting the ceiling and floor but neither of the narrow ends.
17. (Original post by Good bloke)
I suspect you cannot do multiplication very well the answer is 8 cans exactly, though I see your picture shows you are painting the ceiling and floor but neither of the narrow ends.
even with the 8 cans, the answer would still be wrong.
18. (Original post by Alen.m)
even with the 8 cans, the answer would still be wrong.
There is no whole number of cans that costs £96 if the unit price is £11.75. Are you sure you read the answer correctly?
19. (Original post by Alen.m)
Hi guys,
I'm struggling in question below if anyone can give me a hint would be perfect.
A room has dimensions 6.8 metres x 9.2 metres x 2.5 metres. Stephanie wants to paint the walls of the room,. A large tin of paint covers 20m^2 and costs 11.75. Ignoring windows and doors and allowing for two coats of paint, how much will it cost Stephanie to paint the room?
so basically what i've done was calculating the area surface of the room and divide it by 20 to find out how many tins of paint we need to paint the room and then multiply that by 11.75 which gives me a wrong answer.
so the walls alone(without ceiling and floor, as the problem states that Stephanie wants to paint just the walls) are 80m^2 (because two walls are 9.2x2.5 and the others are 6.8x2.5). So for one coat of paint you need 4 tins, thus for two coats you need 8 tins, which will cost you 94 pounds.
20. (Original post by Alen.m)
can you show your working?? how did you get 8 cans exactly??
Paint four walls: Two are 6.8m x 2.5m, two are 9.2m x 2.5m

Total area 80 sq m.

Do it twice - 160sq m

Use 8 cans (at 20 sq m per can)

Buy the paint at £11.75 = £94.

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