1. Volume and Missing Dimension SO 4, 5
Math – Gd. 6
Unit 3
Measurement: Shape and Space
Volume and Missing Dimension SO 4, 5 By
Vernon Savoury

2. Review
The formula for finding the volume of a rectangular prism is v = bwh.
It means base (b) x width (w) x height (h).
Volume is measured in cubic units.

3. Example V = bwh = 8 m x 4 m x 12 m = 384 m3 base (b) = 8 m
width (w) = 4 m
height (h) = 12 m
12 m
V = bwh
= 8 m x 4 m x 12 m
= 384 m3
4 m
8 m

4. What is the missing dimension?
The missing dimension is the base (b).
V = 384 m3
To find the base:
Divide the volume by the width.
384 m3 ÷ 4 m = 96 m2
Divide this answer by the height.
96 m2 ÷ 12 m = 8 m
12 m
4 m l
Using a calculator:
384 ÷ 4 ÷ 12 = 8
The base (b) of the rectangular prism is 8 m.

5. What is the missing dimension?
The missing dimension is the base (b).
V = 384 m3
To find the base:
b = v _
12 m wh
= 384_
12 x 4
4 m
= 384_ l 48
= 8 m
The base (b) of the rectangular prism is 8 m.

6. What is the missing dimension?
V = 120 cm3
V = 20,000 m3 ?
8 cm
20,000 ÷ 40 ÷ 10
10 m
120 ÷ 8 ÷ 5
40 m ?
5 cm
3 cm
24 mm
50 m
12 mm
V = 5184 mm3
18 mm
5184 ÷ 12 ÷ 18 ?

7. Practice base (m) width (m) height (m) Volume (m3) 4 5 6 3 60 8 7 336
224 10
350 9
729 12 14
540 30 80
96,000 40 8 6 4 10 9
120 7
1680