Of the adults in Jefferson County, 10% have had CPR training. For a randomly selected group of adults from this county, how large would the group have to be in order for the probability that at least one group mem-ber has had CPR training to be at least 0.90?
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for this, P[none have had training] ≤ 0.10
firstly solve 0.9^n = 0.1
n*ln 0.9 = ln 0.1
n = ln 0.1 / ln 0.9 = 21.85
to satisfy 0.9^n ≤ 0.1, round up to 22 <---------
firstly solve 0.9^n = 0.1
n*ln 0.9 = ln 0.1
n = ln 0.1 / ln 0.9 = 21.85
to satisfy 0.9^n ≤ 0.1, round up to 22 <---------