Question

Ice is placed around a bowl of water to lower the temperature. The equation D=−7/5t+22 shows the time, t, measured in minutes and temperature, D, measured in degrees Celsius. Which statement is correct?

a)The temperature of the water decreases 5°C every 7 minutes.

b)The temperature of the water increases 7°C every 5 minutes.

c)The temperature of the ice that is around the bowl is 22°C

d)Before cooling begins, the temperature of the water is 22°C

Answer 1

C. Is the answer troll loll

Answer 2

d)Before cooling begins, the temperature of the water is 22°C

Explanation:

Given equation that shows the temperature of the bowl after t minutes,

`D=-(7)/(5)t+22`

Initially ( when ice is not placed ) t = 0,

So, the temperature of the water,

`D=(0) + 22 = 22^(\circ)`

i.e. Option d) is correct.

If t = 7 minutes,

The temperature would be,

`D=-(7)/(5)* 7+22`

`=-(49)/(5)+22`

`=-(49+110)/(5)`

`=(61)/(5)`

`=12.2^(\circ)C`

So, the change in temperature = 12.2° - 22° = -9.8°,

Thus, option a) is incorrect.

If x = 5 minutes,

The temperature would be,

`D=-(7)/(5)* 5+22=-7+22 = 15^(\circ)`

Change in temperature = 15° - 22° = -7°,

So, Option b) is incorrect.

∵ The temperature of the ice must be less than 22°,

Thus, option c) is incorrect.