1. I just want to know if this equation is correct

The # of bacteria growing in meat doubles each day while in a fridge. When you buy the meat, it contains 300 bacteria. Find a function that represents the # of bacteria in the meat after t days

2. If an inflation rate remains at 4% a year, then the amount a dollar is worth decreases by 4% a year

a) assume today a dollar is actually worth $1, at the stated rate of inflation, how much will this dollar be worth after 6 years

b) find a function which describes the value of a dollar after t years

I tried and made a function f(t) = 1 - (1/25)^t but it didnt work

3. A yeast colony is growing exponentially. It starts with 400 individuals and 2 hours later it has 4,000. Find a function describing the amount of yeast in the colony after t hours