PSLE
The graph shows the temperature of water in a pot from 1100 to 11 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 1132 to 1140? Give your answer in °C/min.
(a)
Temperature of water that reached 60°C at 11 16.
From 11 08 to 11 48: 40 min
Duration that the temperature of water that reached 80°C and below = 40 min
(b)
Decrease in temperature of water
From 11 00 to 11 08: 86°C - 80°C = 6°C
From 11 8 to 11 16: 80°C - 60°C = 20°C
From 11 16 to 11 24: 60°C - 45°C = 15°C
From 11 24 to 11 32: 45°C - 40°C = 5°C
From 11 32 to 11 40: 40°C - 30°C =
10°C
From 11 40 to 11 48: 30°C - 20°C =
10°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 11 24 to 11 32 and 11 32 to 11 40. (c)
Change in temperature per minute from 11 32 to 11 40
= 10 ÷ 8
= 1.25°C/min
Answer(s): (a) 40 min; (b) 11 24 to 11 32, 11 32 to 11 40; (c) 1.25°C/min