A homework problem? Remarkably odd-looking distribution... Are you sure that 25, 30, 35, ... are numbers of persons, and not their ages? Why should "adults" = 5*"priors" + 20, I wonder? Nevertheless ... :
On Sat, 26 Oct 2002, Brian Lovins wrote: > You have a sample of 475 adults. The following is a distribution: > > 1 prior - 25 adults 2 priors - 30 adults 3 priors - 35 adults > 4 priors - 40 adults 5 priors - 45 adults 6 priors - 50 adults > 7 priors - 55 adults 8 priors - 60 adults 9 priors - 65 adults > 10 priors - 65 adults Surely this last (10 priors) should read "70 adults"? > Suppose you want to select four adults at random from this > population. What is the probability of getting the following in 4 > selections? > > At least two adults with 5 priors, with replacement. If you're really stuck on this question, start with a simpler question and work up. E.g.: 1. Select one adult at random. What's the probability that s/he has 5 priors? 2. Select two adults. What's the probability that both have 5 priors? 3. Select 3 adults. What's the probability that exactly two of them have 5 priors? That all three of them have 5 priors? Etc. ----------------------------------------------------------------------- Donald F. Burrill [EMAIL PROTECTED] 56 Sebbins Pond Drive, Bedford, NH 03110 (603) 626-0816 [was: 184 Nashua Road, Bedford, NH 03110 (603) 471-7128] . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
