What formula will I use to solve this problem?

Question

The population of bacteria is directly proportional to the temperature. There are about 10 million bacteria at 20 degrees Celsius.

Create a formula for this. What type of variation is this? What is k? How many bacteria will there be at 30 degrees celsius? Where else would I use this?

Answer 1

10 million = 20k

k = 1 half million

= the constant of proportionality

Pop = .5 million times temperature

P = t/2 in millions

it's direct variation

at 30 degrees Celsius, the bacteria population = 30/2 = 15 million