Answer:
The number of buyers on the first day was approximately 324.
Explanation:
In this case we have a initial number of shoppers "C" that we want to know and this grows at a steady rate of 20% per day, like a compound interest, we also know the total number of shoppers after 4 days, so we have the final amount of shoppers. We can use the formula for compound interest in order to calculate the number of shoppers in the first day as shown bellow:
M = C*(1 +i)^(t)
Where M is the total amount of shoppers, i is the growth rate and t is the time elapsed.
671 = C*(1 + 0.2)^(4)
671 = C*(1.2)^4
671 = C*2.0736
C = 671/2.0736 = 323.5918
Since there can't be a 0.59 buyer, we will round the number to 324.