Decide if the following problem is an example of a permutation or a combination. state your rationale. for a study, 4 people are chosen at random from a group of 10 people. how many ways can this be done? a. combination - set of objects arranged in a certain order c. combination - an unordered arrangement of objects b. permutation - set of objects arranged in a certain order d. permutation - an unordered arrangement of objects

c is the final answer! : )

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.