PSLE
The graph shows the temperature of water in a pot from 2100 to 21 48.
- For how many minutes was the temperature of the water 50°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 2132 to 2140? Give your answer in °C/min.
(a)
Temperature of water that reached 40°C at 21 16.
From 21 08 to 21 48: 40 min
Duration that the temperature of water that reached 50°C and below = 40 min
(b)
Decrease in temperature of water
From 21 00 to 21 08: 65°C - 50°C = 15°C
From 21 8 to 21 16: 50°C - 40°C = 10°C
From 21 16 to 21 24: 40°C - 28°C = 12°C
From 21 24 to 21 32: 28°C - 19°C = 9°C
From 21 32 to 21 40: 19°C - 11°C =
8°C
From 21 40 to 21 48: 11°C - 3°C =
8°C
Two 8-minute intervals that the temperature of water decreas
es at the same rate are 21 24 to 21 32 and 21 32 to 21 40. (c)
Change in temperature per minute from 21 32 to 21 40
= 8 ÷ 8
= 1°C/min
Answer(s): (a) 40 min; (b) 21 24 to 21 32, 21 32 to 21 40; (c) 1°C/min