I need with my homework and Im stuck on this one

I'm trying to understand conditional probability more so I can pass my class.

A coin is tossed until we get the pattern HTH. Assume that H appears with probability p. What is the expected number of flips required? [Hint: Condition on the number of flips required to...

I have 7 letters and 6 possibilities with repetition. so that is 7^6 but now they ask me how many word possibilities will not contain one of the letters, how many words will contain one of the letters...

A dental study conducted at the University of Iowa estimated that the probability that a randomly selected 5-year-old child has a cavity is 0.242, the probability that the child has minor caries is...

The probability that it does not coat a BUZZ chocolate bar adequately is 0.11. On any day the machine coats 250 SNAP bars and 500 BUZZ bars.

In a school, the probability that a student takes environmental science and geography is 0.25. The probability that a student takes environmental science is 0.72. What is the probability that a student...