Question 5.426

16. Inspection Time. A U.S. Army drill instructor will perform inspection on 2 soldiers in a squad of 18 soldiers. If both soldiers fail the inspection because their rifles are not clean, the entire squad will have to run a five-mile course in full gear. Three of the 18 soldiers have rifles that are not clean.

  1. Explain whether the drill instructor is using a permutation or a combination.
  2. Find the number of ways that both soldiers will fail the inspection.
  3. Find the probability that the entire squad will have to run a five-mile course in full gear.