Probability question?

a partcular type of tennis racket comes in a midsize and an ovrsize version. 60% of all customers at a certain store want the oversize version. among ten randomly selected customers who want this type of racket, what is the probability that at least six want the oversize? (b)among ten randomly selected, what is the probability that the number who want the ovesize version is within 1 standard deviation from the mean? (c) the store currently has 7 rackets of each version, what is the probability that all of the next 10 customers who want the racket can get the version they want from current stock?