Question

A certain freezing process requires that room temperature should be lowered from 40${}^{\circ }$C at the rate of 5${}^{\circ }$C every hour. What is the room temperature after 10 hours?

• A. 0${}^{\circ }$C
• B. -5${}^{\circ }$C
• C. -10${}^{\circ }$C
• D. -15${}^{\circ }$C

Answer 1

The correct option is C -10${}^{\circ }$C

Initial temperature of room = ${40}^{\circ }C$
Given that the temperature lowers at the rate of $5^{\circ }C$ every hour.

So, the temperature after one hour will be (40 - 5)
The temperature after two hours will be (40 - 5 - 5) i.e. 40 - (5) $\times$2
Similarly, after 10 hours, the temperature will be:
= 40 - (5)$\times$10
= 40 - 50
= $(-10{)}^{\circ }C$

Therefore, after 10 hours the room temperature will be $-{10}^{\circ }C$