O COUNTING AND PROBABILITY Finding the odds in favor and against

Susana v

Espoo

Keith is at the grand opening celebration of a supermarket. He spins a wheel with 10 equal-sized slices, as shown below. The wheel has 7 black slices, 2 grey

slices, and I white slice. When the wheel is spun, the arrow stops on a slice at random. If the arrow stops on the border of two slices, the wheel is spun again.

23

(a) If the arrow stops on a black slice, then Keith wins a gift card. Find the

odds against Keith winning a gift card

to

X

Р

(b) If the arrow stops on a black slice, then Keith wins a gift card. Find the

odds in favor of Keith winning a gift card.

Explanation

Check