PSLE
The graph shows the temperature of water in a pot from 2100 to 21 36.
- For how many minutes was the temperature of the water 50°C and below? Give your answer in min.
- During which two 6-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 2130 to 2136? Give your answer in °C/min.
(a)
Temperature of water that reached 50°C at 21 12.
From 21 12 to 21 36: 24 min
Duration that the temperature of water that reached 50°C and below = 24 min
(b)
Decrease in temperature of water
From 21 00 to 21 06: 85°C - 68°C = 17°C
From 21 6 to 21 12: 68°C - 50°C = 18°C
From 21 12 to 21 18: 50°C - 30°C = 20°C
From 21 18 to 21 24: 30°C - 24°C =
6°C
From 21 24 to 21 30: 24°C - 15°C = 9°C
From 21 30 to 21 36: 15°C - 9°C =
6°C
Two 6-minute intervals that the temperature of water decreas
es at the same rate are 21 18 to 21 24 and 21 30 to 21 24. (c)
Change in temperature per minute from 21 30 to 21 36
= 9 ÷ 6
= 1.5°C/min
Answer(s): (a) 24 min; (b) 21 18 to 21 24, 21 18 to 21 24; (c) 1.5°C/min