Final answer:
To determine the number of pizzas needed, multiply the number of students by the number of pieces per student and then divide by the number of pieces per pizza. The answer is 5 pizzas.
Step-by-step explanation:
To determine how many pizzas to order for the 15 students, we need to calculate the total number of pieces they will need. Each student wants 3 pieces, so we multiply 15 (the number of students) by 3 (the number of pieces per student), which gives us 45 pieces. Since each pizza contains 9 pieces, we divide 45 by 9 to get 5 pizzas.
In conversion factor terms, we can express this as:
1 pizza = 9 pieces
15 students x 3 pieces per student = 45 pieces
45 pieces ÷ 9 pieces per pizza = 5 pizzas