Final answer:
To approximate the number of cruise passengers t years after 2005, with an initial amount of 7.1 million passengers and a 10% growth rate, the formula is N = 7.1(1.10)^t.
Step-by-step explanation:
The student has asked for a formula to approximate the number of cruise passengers in millions, N, t years after 2005. Given the initial amount of 7.1 million passengers and the annual growth rate of 10%
 
To calculate the number of passengers in any given year after 2005, we can use the formula for exponential growth:
 
N = P(1 + r)^t
 
Where:
 
 - P is the initial amount (7.1 million)
  - r is the growth rate (0.10 for 10%)
  - t is the number of years since 2005
  
 
Thus, the formula simplifies to:
 
N = 7.1(1.10)^t
 
Using this formula, we can estimate the number of passengers for any year after 2005 by plugging in the number of years since 2005 as t.