peter plans to build a tree house in his back yard. he needs to know how many square feet of lumber he should buy for the floor. he considers the greatest number of people who will be in the tree house at one time, and decides to allow 20 square feet of floor space per person.
which expression can peter use to determine the size of the floor, in square feet, if n represents the number of people?
20n
20 + n
20 – n
20/n

Anew test for ra is being developed. the test is administered to 750 patients with ra and 750 without ra. for the sake of the question, assume the prevalence of ra in this population is 50%. of the 750 patients with ra, 575 have a positive result. of the 750 patients without ra, 150 have a positive result. what is the positive predictive value of the new test? a575/(575+150) b. 600/(600+ 150) c. 575/(575+125) d. 600/(600+ 125)