PSLE
The graph shows the temperature of water in a pot from 2000 to 20 48.
- For how many minutes was the temperature of the water 55°C and below? Give your answer in min.
- During which two 8-minute intervals did the temperature of water decrease at the same rate? Give your answer in the following format. (Eg 01 00 to 01 15, 01 25 to 01 30)
- What was the change in temperature per minute from 2040 to 2048? Give your answer in °C/min.
(a)
Temperature of water that reached 55°C at 20 16.
From 20 16 to 20 48: 32 min
Duration that the temperature of water that reached 55°C and below = 32 min
(b)
Decrease in temperature of water
From 20 00 to 20 08: 73°C - 67°C = 6°C
From 20 8 to 20 16: 67°C - 55°C = 12°C
From 20 16 to 20 24: 55°C - 50°C = 5°C
From 20 24 to 20 32: 50°C - 39°C =
11°C
From 20 32 to 20 40: 39°C - 29°C = 10°C
From 20 40 to 20 48: 29°C - 18°C =
11°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 20 24 to 20 32 and 20 40 to 20 32. (c)
Change in temperature per minute from 20 40 to 20 48
= 10 ÷ 8
= 1.25°C/min
Answer(s): (a) 32 min; (b) 20 24 to 20 32, 20 24 to 20 32; (c) 1.25°C/min