Question

Gina and Danny are playing a subtraction card game. In the card game, each player takes turns pulling two cards, one at a time, from a deck of cards. If the first card minus the second card is positive, the player keeps those cards. If the answer is zero or negative, the player loses those cards, and the cards go back in the deck.

There are only 10 cards in the deck, which have the following numbers:

0.1 0.2 0.3 0.4 0.5
-0.1 -0.2 -0.3 -0.4 -0.5

(a) If a player gets a first card that is a positive number, what must the second card be in order for the player to keep the cards? Explain your reasoning.
(b) Gina -0.2 pulls as her first card. What must her second card be in order for her to have a positive answer? List all correct answers and explain why or show your work.
(c) Danny also pulls an -0.2 as his first card. He pulls the second card and says he has to put the cards back in the deck because he got a negative answer. What card could Danny have pulled? List all correct answers and explain why or show your work.

Answer 1

(a) if the player pulls 0.5, then they must get a -0.4 or higher in order to keep going.
(b)Gina must pull a 0.3 or higher to keep going. -0.2+0.3=0.1, -0.2+0.4=0.2, -0.2+0.5=0.3.
(c)Danny may have pulled a 0.2 or lower. -0.2+0.2=0, -0.2+0.1=-0.1, -0.2+-0.1=-0.3,-0.2+-0.3=-0.5, -0.2+-0.4=-0.6, -0.2+-0.5=-0.7.

Hope this helps!