Question

Jill is ordering a sandwich at a restaurant, and the server tells her that she can have up to five toppings: jalapeños, tomatoes, spinach, mushrooms, and pickles. Since she cannot decide how many of the toppings she wants, she tells the server to surprise her. If the server randomly chooses which toppings to add, what is the probability that Jill gets just jalapeños and spinach?

Answer 1

Jill can either only have 1 out of 5 toppings, 2 out of 5 toppings, until 5 out of 5 toppings. The total combinations would be:

total = 5C1 + 5C2 + 5C3 + 5C4 + 5C5

total = 31 combinations

 

So the probability that Jill will get just jalapenos and spinach (1 combination) is:

Probability = 1/31 = 0.03225 = 3.23%