1. moazzam07

2. anonymous

3. anonymous

Multiply by 20

4. mathstudent55

Each dimension is in the scale 1:20 That means each real length is 20 times the drawing size.

5. mathstudent55

First, what is 4 inches * 20 ? 5 inches * 20 ?

6. anonymous

So just think of the scale as a fraction 1 over twenty or 1/20

7. anonymous

Exactly just multiply by 20

8. moazzam07

100 and 80

9. moazzam07

@mathstudent55 its 80 and 100

10. anonymous

Yes

11. mathstudent55

Correct. The real dimensions of the room are 80 inches and 100 inches. Now we need to find the area. Since the room is a rectangle, you use the formula for the area of a rectangle A = LW

12. moazzam07

100 x 80 ?

13. mathstudent55

Yes. What do you get?

14. moazzam07

8000

15. mathstudent55

A = 100 in. * 80 in. = 8000 in.^2 Now we have the are in square inches. The problem wants the are in square feet, so we need to convert.

16. moazzam07

ok how do we convert

17. mathstudent55

We need to figure out how many square inches there are in a square foot.

18. mathstudent55

First, do you know how many inches there are in a foot?

19. moazzam07

144

20. moazzam07

12

21. mathstudent55

|dw:1439780872466:dw|

22. mathstudent55

Correct. |dw:1439780923987:dw|

23. moazzam07

There are 144 square inches in a square foot

24. mathstudent55

Correct also.

25. mathstudent55

|dw:1439780976584:dw|

26. moazzam07

ok

27. mathstudent55

|dw:1439781017032:dw|

28. mathstudent55

A square 1 ft by 1 ft has an area 1 ft * 1 ft = 1 square foot. 1 foot = 12 inches, so A square 12 inches by 12 inches has an area 12 in. * 12 in. = 144 square inches. This shows that 1 square foot = 144 square inches

29. moazzam07

would i do 8000 / 12?

30. mathstudent55

Ok, now we need to convert 8000 square inches into square feet. We know the conversion factor is 144. The question we have is do we multiply 8000 by 144 or do we divide 800 by 144? We can figure it out by reasoning it out. 1 square foot is the same size as 144 square inches. This means that 1 square foot is much larger than a square inch, so much so that it takes 144 square inches to equal 1 square foot. That means that for the same are, it will take many more square inches to fill it up than square feet. Then, if we divide the number of square inches by 144, we get square feet. $$A = LW = 80 ~in. \times 100~ in. = 8000 ~in.^2$$ $$A = \dfrac{8000}{144}~ft^2$$

31. mathstudent55

Divide 8000 by 144, not by 12.

32. moazzam07

55.55555555555556

33. moazzam07

@mathstudent55 is the final answer 55.55556 ft ^2?

34. moazzam07

@pooja195 is the final answer 55.55556 ft ^2?

35. mathstudent55

Correct.

36. moazzam07

ok thanks @mathstudent55

37. mathstudent55

yw

Find more explanations on OpenStudy