Afair coin is tossed three times. a player wins $1 if the first toss is a head, but loses $1 if the first toss is a tail. similarly, the player wins $2 if the second toss is a head, but loses $2 if the second toss is a tail, and wins or loses $3 according to the result of the third toss. let the random variable x be the total winnings after the three tosses (possibly a negative value if losses are incurred). (a) construct the probability mass function