Hi,
These steps apply to the TI-GC:
1. Manually form the inequality, i.e., P(X <= 5) >
0.9.
2. Go to the equation editor and enter the 'binomcdf'
command, i.e.,
binomcdf(X, 0.05, 5).
3. Show the table of values, via 2ND, GRAPH buttons.
4. Scroll down the values until you reach the row with a
value less than 0.9. The row just above is the answer, i.e., 63
trials.
Thanks.
Cheers,
Wen Shih