PSLE
The graph shows the temperature of water in a pot from 1300 to 13 42.
- For how many minutes was the temperature of the water 60°C and below? Give your answer in min.
- During which two 7-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 1328 to 1335? Give your answer in °C/min.
(a)
Temperature of water that reached 40°C at 13 14.
From 13 07 to 13 42: 35 min
Duration that the temperature of water that reached 60°C and below = 35 min
(b)
Decrease in temperature of water
From 13 00 to 13 07: 75°C - 60°C = 15°C
From 13 7 to 13 14: 60°C - 40°C = 20°C
From 13 14 to 13 21: 40°C - 32°C = 8°C
From 13 21 to 13 28: 32°C - 27°C = 5°C
From 13 28 to 13 35: 27°C - 20°C =
7°C
From 13 35 to 13 42: 20°C - 13°C =
7°C
Two 7-minute intervals that the temperature of water decreas
es at the same rate are 13 21 to 13 28 and 13 28 to 13 35. (c)
Change in temperature per minute from 13 28 to 13 35
= 7 ÷ 7
= 1°C/min
Answer(s): (a) 35 min; (b) 13 21 to 13 28, 13 28 to 13 35; (c) 1°C/min