Biostatistics in health care

Question

 a recent study reported that the prevalence of obesity is 45% in children ages 6-12. If 15 children were analyzed what is the probability that 7 are obese?

Answer 1

Because you are sampling from a "large" population we can use a binomial distribution for our calculations.

 

P(of selecting an obese child) = .45. P(not selecting)=1-.45=.55

 

the probability would b(7;15,.45), that is getting exactly 7 successes in 15 trials with the probability of success=.45

 

To get a numerical answer you can use a binomial distribution table or the binomial formula:

 

b(r;n,p)=( n!/[(r!)(n-r)!] )p^r(1-p)^(n-r)

 

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