Mathematics

Problem

The temperature inside a refrigerator is

4^{\circ}\text{C}

at noon and falls by

2.5^{\circ}\text{C}

each hour thereafter. What is the least integer value of

h

(in hours) after noon at which the temperature will be below

-6^{\circ}\text{C}

? a) 4 b) 3 c) 5 d) 6