Dave wants to estimate the number of students in the middle school who like history He wants to determine a random sample by asking 40 students. How should Dave collect his information?

A ask students at the library

B ask students from history classes

C ask students from the seventh grade

D ask students as they leave school for the day

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?