1. 26 Math Review Part 2 Inches to Feet & Areas

2. Division
80 ÷ 5 = 16 Also written as: 5 80 1 6 5 3 30

3. Multiplication and Division
6 x 5 x 4 = 120
4 x 6 x 5 = 120
10 ÷ 5 x 4 = ?
10 ÷ (5 x 4) = 1/2
(10 ÷ 5) x 4 = 8
(10 x 4) ÷ 5 = 8

4. Multiplication and Division
0.56 x 0.35 = ?
0.56 x 0.35 = .196
0.56 ÷ 0.35= ?
0.56 ÷ 0.35 = 1.6
0.56 x =
0.56 ÷ = 80
0.007 ÷ 0.56 =

5. Multiplication and Division
What is 6 feet 3 inches in feet?
1 foot = 12 inches
3 inches = 3 ÷ 12 = 0.25 feet
= 6.25 feet

6. Area Calculations
For Squares and rectangles the area (A) is equal to length (L) x width (W) or A = L x W
Width
Length

7. Area Calculations A = L x W Square L = W = 3
3 x 3 = 9 Square Something
Width = 3
Length = 3

8. Area Calculations
For Squares and rectangles the area (A) is equal to length (L) x width (W) or A = L x W
Width = 6 feet 3 inches
Length = 3 feet

9. Area Calculations
For Squares and rectangles the area (A) is equal to length (L) x width (W) or A = L x W
Width = 6 feet 3 inches =
6 + (3 ÷ 12) = 6.25 feet
Length = 3 feet
A = L x W = 3 x 6.25 = square feet

10. Area of a Triangle
For any triangle with a right angle the area is the length multiplied by the width (of the two legs meeting at the right angle) divided by 2.

11. Area of a Right Triangle
For any triangle with a right angle the area is the length multiplied by the width (of the two legs meeting at the right angle) divided by 2.

12. Area of a Right Triangle
For any triangle with a right angle the area is the length multiplied by the height of the two legs where the right triangle is divided by 2.
90o
90o
90o
90o
90o = right angle

13. Area of a Triangle
For any triangle with a right angle the area is the length multiplied by the height of the two legs where the right triangle is divided by 2.
90o
90o
Length
90o
90o
Width

14. Area of a Triangle
A = hb X b ÷ 2

15. Area of a Triangle
A = hb X b ÷ 2 hb
90o
90o

16. Area of a Triangle
A = hb X b ÷ 2 hb
90o
90o b

17. Area of a Triangle A = hb X b ÷ 2 = hb= 6’ 90o 90o b = 14’
A = 6 X 16 ÷ 2 = 48 Sq. Ft.

18. Area of a Triangle Calculate the wall area for the following drawing:
3.66 ft
8.0 ft
18.75 ft

19. Area of a Triangle Calculate the wall area for the following drawing:
3.66 ft
8.0 ft X ft = 150 ft2
8.0 ft
18.75 ft

20. Area of a Triangle Calculate the wall area for the following drawing:
3.66 ft hb b
18.75 ft
8.0 ft
3.66 ft X ft ÷ 2 = 34.3 ft2

21. Area of a Triangle Calculate the wall area for the following drawing:
3.66 ft
34.3 ft2
8.0 ft
150 ft2
18.75 ft

22. Area of a Triangle Calculate the wall area for the following drawing:
3.66 ft
34.3 ft2
8.0 ft
150 ft2
150 ft ft2 = ft2
18.75 ft

23. Area of a Circle
A = 3.14 x R x R
Radius = R
Diameter = 2 x R

24. Area of a Circle A = 3.14 x R x R Radius = ½ R = 4 inches
Diameter = 8 inches
A = 3.14 x 4 x 4
A = square inches

25. Area of a Circle A = 3.14 x R x R Radius = ½ R = 4 inches
Diameter = 8 inches
A = 3.14 x 4 x 4
A = square inches

26. Area of a Circle A in square inches = A in square feet 12 x 12 = 144
50.24 ÷ 144 = ?
A = square inches …

27. Measuring Areas in Cubic Feet

28. Step 1 Finding the Area/Volume in Cubic Feet
Calculate the wall area for the following drawing:
3.66 ft
34.3 ft2
8.0 ft
150 ft2
150 ft ft2 = ft2
18.75 ft

29. Step 2 Find the Length
184.3 ft2

30. Step 2 Find the Length
184.3 ft2
40.3 ft

31. Step 3 Multiply Area X Length
184.3 ft2 X 40.3 ft = 7, ft3
40.3 ft

32. Converting Units
Converting 6 inches of Mercury into Inches of Water Inches of Mercury are multiplied by 13.6 to get inches of water 6” of Mercury = 13.6 x 6 = 81.6 inches of water Note: 81.6” ÷ 12” = feet of water = 6.8’

33. Converting Units
Convert 82 Inches of Water to Inches of Mercury Inches of water are multiplied by to get Inches of Mercury 82” x = 6.027” of Mercury

34. Converting Units
LPS x = CFM CFM x 2.12 = LPS HP x = Kilowatts 1Watt = Btu/h Ft of H2O x = psi psi x 2.31 = Ft of H2O [F0 – 32] x 5/9 = C0 [C0 x 9/5] + 32 = F0 h = Ppsia ÷ Ppsia = psi Tons of Refrigeration = HP x Tons of Refrigeration = BTU/minute x 200 Note: HP x = Btu/minute x 200

35. Converting Units
Square inches are divided by 144 to get square feet 72 in2 = ? Ft2 72 ÷ 144 = 0.5 Ft2 Note: Ft2 x 144 = in2

36. Using Equations 3
600
3 x 200 = = 2
400
2 x 200 2
400 = 3
600

37. Using Equations Fan Law
CFMnew
RPMnew =
CFMold
RPMold
CFMold
RPMold =
CFMnew
RPMnew

38. Using Equations = x = x x = 3 600 2 400 3 600 400 400 2 400 3 400 600

39. Using Equations Fan Law
CFMnew
RPMnew =
CFMold
RPMold
CFMnew x =
RPMold
RPMnew
CFMold