Four thousand bass were stocked in a certain lake with no bass population If the population of bass is expected to grow at a rate of 22 per year how long will it take the population to double Step 1 The time in years required for a population to double is given by t Step 2 Substitute r t In 2 t Evaluate rounding to the nearest tenth yr into the formula In 2 where r is the annual growth rate r annual growth rate