Consider a binomial experiment with n=6 trials where the probability of success
on a single trial is p=0.85.
(a) Find P(r=7).
Either use a TI-83 or 84 graphing calculator or the long formula.
If you use a TI graphing calculator:
press 2nd vars and scroll down to highlight binompdf( [not binomcdf]
[if your calculator is newer then trials:6, p:0.85, x value:7, paste, enter]
press enter
Answer: 0
Why is it 0? Because it is impossible to get 7 successes out of only 6 trials!
(Bet you already knew that, right? lol)
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(b) Interpretation If you conducted the experiment and got fewer than 2 successes, would you be surprised?
"Fewer than 2" must be interpreted as "1 or fewer"
press 2nd vars and scroll down to highlight binomcdf( [not binompdf this time]
press enter
[if your calculator is newer then trials:6, p:0.85, x value:1 paste, enter]
press enter
Answer: 3.8728125E-4 = 0.00038728125
Yes we would be surprised because that probability is less than 0.05. We should
be surprised at anything happening that happens less than 5% of the time.
Edwin