PSLE
The graph shows the temperature of water in a pot from 2200 to 22 48.
- For how many minutes was the temperature of the water 80°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 2232 to 2240? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 22 16.
From 22 08 to 22 48: 40 min
Duration that the temperature of water that reached 80°C and below = 40 min
(b)
Decrease in temperature of water
From 22 00 to 22 08: 94°C - 80°C = 14°C
From 22 8 to 22 16: 80°C - 60°C = 20°C
From 22 16 to 22 24: 60°C - 47°C = 13°C
From 22 24 to 22 32: 47°C - 31°C = 16°C
From 22 32 to 22 40: 31°C - 25°C =
6°C
From 22 40 to 22 48: 25°C - 19°C =
6°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 22 24 to 22 32 and 22 32 to 22 40. (c)
Change in temperature per minute from 22 32 to 22 40
= 6 ÷ 8
= 0.75°C/min
Answer(s): (a) 40 min; (b) 22 24 to 22 32, 22 32 to 22 40; (c) 0.75°C/min