Final answer:
Based on the sample where 45 out of 60 students preferred pizza, for a class of 1000, the cafeteria staff should prepare 750 servings of pizza.
Step-by-step explanation:
The calculation to determine how many servings the cafeteria staff should prepare for a class of 1000, based on the preference revealed by a random sample, requires us to use a proportion. In the random sample, 45 out of 60 seventh grade students said they prefer pizza for lunch. This sets a proportion of preference for pizza at 45/60, which simplifies to 3 out of 4 students, or 75%. We can apply this percentage to the class of 1000 students to predict their preferences.
To find out how many pizzas the cafeteria should prepare for 1000 students, we multiply 1000 by the fraction 3/4:
1000 students × 3/4 = 750 servings of pizza.
Therefore, the cafeteria staff should prepare 750 servings of pizza to cater to the preferences of a class of 1000 seventh grade students.