What length of a certain metal wire of diameter 0. 15 mm is needed for the wire to have a resistance of 15 ω? the resistivity of this metal is 1. 68 × 10-8 ω · m.

Concerned about campus safety, college officials want to estimate the percentage of students who carry a gun, knife, or other such weapon. how many randomly selected students must be surveyed in order to be 95 % confident that the sample percentage has a margin of error of two percentage points?