Step 1 :This is a combination problem. In a combination, order does not matter. We are choosing 4 students out of 33, so we need to calculate the number of combinations of 33 taken 4 at a time. The formula for combinations is \(C(n, k) = \frac{n!}{k!(n-k)!}\), where n is the total number of items, k is the number of items to choose, and ! denotes factorial.
Step 2 :Let's substitute the given values into the formula. Here, n = 33 and k = 4.
Step 3 :Calculate the factorial of n, k, and (n-k).
Step 4 :Substitute these values into the formula to get the number of combinations.
Step 5 :The number of different ways that an instructor can choose 4 students from a class of 33 students for a field trip is \(\boxed{40920}\).