PSLE
The graph shows the temperature of water in a pot from 1800 to 18 42.
- For how many minutes was the temperature of the water 55°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 1835 to 1842? Give your answer in °C/min.
(a)
Temperature of water that reached 55°C at 18 14.
From 18 14 to 18 42: 28 min
Duration that the temperature of water that reached 55°C and below = 28 min
(b)
Decrease in temperature of water
From 18 00 to 18 07: 88°C - 74°C = 14°C
From 18 7 to 18 14: 74°C - 55°C = 19°C
From 18 14 to 18 21: 55°C - 47°C = 8°C
From 18 21 to 18 28: 47°C - 34°C =
13°C
From 18 28 to 18 35: 34°C - 17°C = 17°C
From 18 35 to 18 42: 17°C - 4°C =
13°C
Two 7-minute intervals that the temperature of water decreas
es at the same rate are 18 21 to 18 28 and 18 35 to 18 28. (c)
Change in temperature per minute from 18 35 to 18 42
= 7 ÷ 7
= 1°C/min
Answer(s): (a) 28 min; (b) 18 21 to 18 28, 18 21 to 18 28; (c) 1°C/min