Question

A freezing system starts cooling the room at the rate of 4℃ per hour. If at the

beginning, the temperature of the room is 30 ℃, find the number of hours it takes

to lower down the room temperature to – 2 ℃.​

Answer 1

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Answer 2

Answer:

9 hours

Step-by-step explanation:

we can use the concept of A.P (arithmatic progression)

ATQ,

an = -2, a = 30, d = -4, n = ?

an = a + (n-1)d

-2 = 30 + (n-1)(-4)

-2-30 = -4n + 4

-32-4 = -4n

-36 = -4n

n = -36/-4 = 9

hence, it would take 9 hours for the temperature to be -2°C