PSLE
The graph shows the temperature of water in a pot from 1500 to 15 48.
- For how many minutes was the temperature of the water 70°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 1532 to 1540? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 15 16.
From 15 08 to 15 48: 40 min
Duration that the temperature of water that reached 70°C and below = 40 min
(b)
Decrease in temperature of water
From 15 00 to 15 08: 87°C - 70°C = 17°C
From 15 8 to 15 16: 70°C - 60°C = 10°C
From 15 16 to 15 24: 60°C - 52°C = 8°C
From 15 24 to 15 32: 52°C - 40°C = 12°C
From 15 32 to 15 40: 40°C - 34°C =
6°C
From 15 40 to 15 48: 34°C - 28°C =
6°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 15 24 to 15 32 and 15 32 to 15 40. (c)
Change in temperature per minute from 15 32 to 15 40
= 6 ÷ 8
= 0.75°C/min
Answer(s): (a) 40 min; (b) 15 24 to 15 32, 15 32 to 15 40; (c) 0.75°C/min