OK, if someone is using the pill, which is 99% effective, while also using spermicide, which is 94% effective, what is the total effectiveness of BOTH of the methods combined. And, for extra credit, why the heck haven't I had my period yet?
2007-01-17 05:24:31 · 2 answers · asked by True Dat 4 in Science & Mathematics ➔ Mathematics
Really, I am interested in how to figure out the statistical side of the question. 10 years out of college, and have forgotten.
2007-01-17 05:36:39 · update #1
P(pill is effective or spermicide is effective) = P(pill is effective) + P(spermicide is effective) - P(pill is effective and spermicide is effective)
= 0.99 + 0.94 - P(pill is effective)P(spermicide is effective) (it is probably safe to assume that these two methods are independent.)
= 0.99 + 0.94 - (0.99)(0.94)
= 0.9994 or 99.94% effective.
People do call me doctor, but I'm not that kind of doctor, so I can't help you on the extra credit ;-).
2007-01-17 05:47:32 · answer #1 · answered by blahb31 6 · 0⤊ 0⤋
extreme stress causes women to miss their periods, if you haven't been under alot of stress lately, then you're probably pregnant. it happens. go take a pregnancy test.
2007-01-17 05:30:44 · answer #2 · answered by Anonymous · 0⤊ 0⤋