Quote:
Originally Posted by Mystery Man
LOL you need to go back to school mate. It says 98% that's 2 percent so just because its over 5 years doesnt mean u make it 2*5... its still 2%
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The figure they give is for one year only. In order to get the number for x number of years you calculate 1 minus the probability of NOT getting pregnant raised to the xth power. So in this case 1 minus (.98 raised to the 5th power). .98^5 is .9039. Then you subtract that from one which is .0961 so 9.61% which rounds to 10%.
If there were a 10% chance of getting pregnant in any one year then the chance of getting pregnant in a 5 year period would be 1-(.9^5) which is 41%.
You are right that it is not 2*5 but it just looks like that for small numbers (2%, for example)