Upon reconsidering the above problem, the psychologist decides that the age of the child may affect the attention span. Consequently, the psychologist randomly assigns fifteen 10 year olds, fifteen 8 year olds, fifteen 6 year olds, and fifteen 4 year olds to watch one of three commercials, and their attention spans are measured.

What is the smallest integer n such that n\sqrt{2} is greater than 20

Jack lives on a farm and has a large backyard. the area of his rectangular backyard is of a square mile. if the width of the yard is of a mile, what fraction of a mile is the length of the rectangular backyard?

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?