PSLE
The graph shows the temperature of water in a pot from 1400 to 14 48.
- For how many minutes was the temperature of the water 60°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 1440 to 1448? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 14 16.
From 14 16 to 14 48: 32 min
Duration that the temperature of water that reached 60°C and below = 32 min
(b)
Decrease in temperature of water
From 14 00 to 14 08: 86°C - 75°C = 11°C
From 14 8 to 14 16: 75°C - 60°C = 15°C
From 14 16 to 14 24: 60°C - 41°C = 19°C
From 14 24 to 14 32: 41°C - 29°C =
12°C
From 14 32 to 14 40: 29°C - 13°C = 16°C
From 14 40 to 14 48: 13°C - 1°C =
12°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 14 24 to 14 32 and 14 40 to 14 32. (c)
Change in temperature per minute from 14 40 to 14 48
= 2 ÷ 8
= 0.25°C/min
Answer(s): (a) 32 min; (b) 14 24 to 14 32, 14 24 to 14 32; (c) 0.25°C/min