Right before the fifth race at Santa Anita, the word got out that one of these horses was going to win the race:
Lightning Bolt: a 2-1 shot
Golden Honey: a 3-1 shot
Matchmaker: a 4-1 shot
Assuming this tip is true, how much would Alex have to bet on each of the three horses to be assured of coming out with a $39 profit?
Initially a box contained 6 blue pens, 8 black pens and 3 red pens.
You blindly picked up a pen.
(a) What is the probability that it was a blue pen?
Later some additional blue pens were put in the box.
The probability of selecting a blue pen became then 50%.
(b) How many blue pens were added to the box?