1. A dental inspector finds that about 20% of children of a certain area have tooth decay. What is the probability that out of 6children examined, only the first,third and fifth will have tooth decay?
-> i got (0.2)^2(0.8)^3 =64/3125 but the answer is 64/3125. What am i missing??
2. On the average a typist has to correct one word in 800words. Assuming that a page contains 200words, find the probability of more than one correction per page.
-> i got
1- [200C1(799/800)^199(1/800) + 200C0(799/800)^200] = 0.0264
But answer is 0.0625