Question

According to a recent study, 10 % of adult smokers started smoking before 21 years old. A random sample of 6 smokers age 21 years or older is selected, and the number of smokers who started smoking before 21 is recorded. Calculate the following probabilities. Round solutions to four decimal places, if necessary.

1. The probability that at least 3 of them started smoking before 21 years of age is

P(x≥3)=

2. The probability that at most 4 of them started smoking before 21 years of age is

P(x≤4)=

3. The probability that exactly 5 of them started smoking before 21 years of age is

P(x=5)=

Answer 1

Use excel formula "=BINOM.DIST(x, n, p, FALSE)"

r	Excel formula	P(x=r) [rounded to four decimal places]
0	=BINOM.DIST(0, 6, 0.10, FALSE)	0.5314
1	=BINOM.DIST(1, 6, 0.10, FALSE)	0.3543
2	=BINOM.DIST(2, 6, 0.10, FALSE)	0.0984
3	=BINOM.DIST(3, 6, 0.10, FALSE)	0.0146
4	=BINOM.DIST(4, 6, 0.10, FALSE)	0.0012
5	=BINOM.DIST(5, 6, 0.10, FALSE)	0.0001
6	=BINOM.DIST(6, 6, 0.10, FALSE)	0.0000

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