I need help with these three problems.

1.An urn containsninered balls,ninewhite balls, andnineblue balls, and sample ofsixballs is drawn at random without replacement.Compute the probability that all of the balls in the sample are the same color. (Round your answer to four decimal places.)

2.Is it possible for a graph with 10 vertices and55edges to be simple? Y/N and explain why.

3.A multiple choice test consists ofsevenquestions, each of which hasfivechoices. Each question has exactly one correct answer.William guesses randomly at each answer. What is the probability that he getsfiveor fewer questions correct? (Round your answer to four decimal places.)