PSLE
The graph shows the temperature of water in a pot from 1700 to 17 30.
- For how many minutes was the temperature of the water 50°C and below? Give your answer in min.
- During which two 5-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 1720 to 1725? Give your answer in °C/min.
(a)
Temperature of water that reached 40°C at 17 10.
From 17 05 to 17 30: 25 min
Duration that the temperature of water that reached 50°C and below = 25 min
(b)
Decrease in temperature of water
From 17 00 to 17 05: 62°C - 50°C = 12°C
From 17 5 to 17 10: 50°C - 40°C = 10°C
From 17 10 to 17 15: 40°C - 32°C = 8°C
From 17 15 to 17 20: 32°C - 25°C = 7°C
From 17 20 to 17 25: 25°C - 14°C =
11°C
From 17 25 to 17 30: 14°C - 3°C =
11°C
Two 5-minute intervals that the temperature of water decreas
es at the same rate are 17 15 to 17 20 and 17 20 to 17 25. (c)
Change in temperature per minute from 17 20 to 17 25
= 11 ÷ 5
= 2.2°C/min
Answer(s): (a) 25 min; (b) 17 15 to 17 20, 17 20 to 17 25; (c) 2.2°C/min