How many plants would you predict will be in the pond on day 22?

To predict the number of plants in the pond on day 22, I would need information on the initial number of plants, the growth rate, and any potential limiting factors. If the plants double in number daily, for example, you could calculate the total by using the formula ( \text{initial number} \times 2^{21} ) (since day 1 is the starting point). Without specific data, it's impossible to provide an accurate prediction.