Simple Calculus

What should be the ₆C¹⁴ content (in percent of y₀) of a fossilized tree that is claimed to be 7000 years old?

Round your answer to the nearest integer.

A thermometer, reading 8degC , is brought into a room whose temperature is 22degC. Two minutes later the thermometer reading is 19 degC. How long will it take until the reading is practically 22 degC, say,21.8 degC?