What power do I need to charge 100 aph 100% whith a system runnig 5 aph all time? Real Life Problems: If I have 100 entries in a table which can be either (right or wrong) and I will know whether each entry is (right or wrong) if I examine that particular entry, but how do I figure out  1) how many entries I have to check 2) what data I need about the 100 entries to have a 90% probability that all the 100 entries being correct (right)?