Question

please tell the answer​

Answer 1

i) temperature after 4 hours = 8° C

ii) required time = 7 hours

Explanation:

The liquid is cooled at the rate of 3° C per hour

∴ in 4 hours, it will be cooled (4 × 3°) C = 12° C in total

Starting temperature = 20° C

∴ after 4 hours, its temperature will be

= 20° C - 12° C

= 8° C

Let after x hours, the temperature will be - 1° C

Then, 20 - 3 × x = - 1

⇒ 20 - 3x = - 1

⇒ 3x = 21

⇒ x = 21/3

⇒ x = 7

∴ after 7 hours, the temperature will be - 1° C

Answer 2

Step-by-step explanation:

hope it helps you.

Thank you.