"Fewer than 3" means "2 or fewer".
On a TI-83 or TI-84
press 2ND VARS,
scroll down to binomcdf(
press ENTER
Newer TI calculators have more features than older ones,
but all boil down to the same, I,e., binomcdf(7,0.15,2)
trials = 7,
the probability p of 1 success in 1 trial is 0.15,
The x value of the number of desired successes or fewer is 2,
If you see "Paste", highlight it and click ENTER, otherwise
make sure your calculator reads
binomcdf(7,0.15,2)
Then click ENTER and read the answer:
0.9262348399
[Note: if you got 0.2096507602, you scrolled to "binompdf(" not
"binomcdf(", which gave the probability of EXACTLY 2 successes,
not 2 or fewer.]
Edwin
