1 Singapo
TRY
A rectangular tank 45 cm long, 28 cm wide and 30 cm high is filled with water
up to of its height Water from a tap flows into the tank at a rate of 2.5 litres
per minute. At this rate, how much water is in the tank after 5 minutes? Give
your answer in litres.
Volume of water in tank
30 cm
Х
Х
28 cm
cm
45 cm
l
Volume of water from tap =
X Х
l
Volume of water in tank =
l
Workbook B:
Practice 2,
pages 73-80
There are
e of water in the tank after 5 minutes.
Lesson 2 Solving Word Problems
97
Answer:
This can be performed by simple mental arithmetic. I litre of water (or any other fluid) takes up a space 10cm x 10 cm x 10 cm. 10cm^3, or 1000cc. How many times does 10cm fit into each of the dimensions of your tank? 5, 2 and 3.3. You can multiply those in your head, can’t you?
However, you may prefer to multiply 50 x 20 x 33, and divide by 1000 (10^3)
You can also multiply 0.50 x 0.20 x 0.33 (metres) and arrive at the capacity in m^3, then multiply by 1,000.
The first method gets you straight to litres (dm^3) decimetre cubed. 10cm ^3
The second to cc, which must be divided by 1,000, since there are 1,000 cc (ml) in a litre.
The third gives you cubic metres, and a cubic metre is 1,000 litres…
I heard a lecturer at a college I worked at refer to dm as decametres. He was wrong.