PSLE
The graph shows the temperature of water in a pot from 1600 to 16 42.
- For how many minutes was the temperature of the water 45°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 1635 to 1642? Give your answer in °C/min.
(a)
Temperature of water that reached 45°C at 16 14.
From 16 14 to 16 42: 28 min
Duration that the temperature of water that reached 45°C and below = 28 min
(b)
Decrease in temperature of water
From 16 00 to 16 07: 84°C - 65°C = 19°C
From 16 7 to 16 14: 65°C - 45°C = 20°C
From 16 14 to 16 21: 45°C - 29°C = 16°C
From 16 21 to 16 28: 29°C - 18°C =
11°C
From 16 28 to 16 35: 18°C - 12°C = 6°C
From 16 35 to 16 42: 12°C - 1°C =
11°C
Two 7-minute intervals that the temperature of water decreas
es at the same rate are 16 21 to 16 28 and 16 35 to 16 28. (c)
Change in temperature per minute from 16 35 to 16 42
= 7 ÷ 7
= 1°C/min
Answer(s): (a) 28 min; (b) 16 21 to 16 28, 16 21 to 16 28; (c) 1°C/min