Question 211052
If 4.1% of the population of Finland lives to the age of 90, what is the probability that of 1000 Finlandians:
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The populatin mean is 0.041; the standard deviation is sqrt(0.041*0.959)
= 0.1983

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I'm using a TI calculator to get the answers below.
a) between 30 and 40 will live to be 90 years old?
Ans: binomcdf(1000,0.041,40) - binomcdf(1000,0.041,29)= 0.4493..
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b) more than 80 of them will live to be 90 years old?
Ans: 1 - binomcdf(1000,0.041,80) = 0.0000000099057
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c) less than 20 of them will like to be 90 years old?
Ans: binomcdf(1000,0.041,19) = 0.00007855
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Cheers,
Stan H.