The marketing department of Low-Brau, a microbrewery that makes what it considers an excellent light beer, asked 20 volunteers, individually, to taste 5 types of light beer (one of which was the company's brand and the others being competitor brands) and report which one they liked the best. Out of those 20 people, seven said they liked Low-Brau's light beer the best. The taste test was "blind" in that the beers were served in identical glasses and the volunteers were not told which of the 5 beers they tasted was Low-Brau's. If there really is no detectable difference in the taste of the light beers (that is, if customers are simply randomly guessing) what is the chance that exactly seven volunteers would rate Low-Brau's as the best? Report your answer to three decimal places. Hint: This is a binomial distribution