If 30 percent of people use the library in one year find the probabilities for a sample of 15 people
A. At most 7 used the library
On your TI-83 or 84
Press 2ND
Press VARS
Scroll down to binomcdf(
Press ENTER
If you have a newer TI calculator, enter
trials:15
p:.3
x value:7
Highlight Paste
Press ENTER
Press ENTER again
If you have an older TI calculator, make it read
binomcdf(15,.3,7)
Press ENTER
You read .9024761739
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B. exactly 7 used the library
Same as above, except this time,
Scroll down to binompdf(, instead of binomcdf(
.0811300333
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C. At least 5 used the library
That's the complement of 4 or fewer.
So find
binomcdf(15,.3,4) as above.
Get .5154910592
Subtract from 1
.4845089408 <-- final answer
Edwin