# MathBench>Probability

## Mice with Fangs: Intro to Punnett Squares

So the point here is that the Punnett Square just gives us all the possible combinations all two sets of objects / phrases / conditions / whatever. You list one complete set along the top, and the other complete set across the side.

Of course it's possible that the two sets might have some elements in common. For example, when I go to the Chez Punnett, I may not care what 2 dishes I eat - instead I might just care what they cost. So my square might look like this:

\$24
(Shrimp)

\$24
(Trout)

\$28 (Gratin) \$28
(Turkey)
\$37
(Hen)
\$13
(Choc Mink)
\$37 \$37 \$41 \$41 \$50
2. \$13
(Choc Cake)
\$37 \$37 \$41 \$41 \$50
\$17
(Popsicle)
\$41 \$41 \$45 \$45 \$54
\$17
(Gelato)
\$41 \$41 \$45 \$45 \$54
\$17
(Croissant)
\$41 \$41 \$45 \$45 \$54

Notice that many meals cost the same amount when totalled up.

### If I ordered a meal at random from Chez Punnett, what is the chance I would end up paying \$41?

(To make this problem interactive, turn on javascript!)

• I need a hint ... : There are 10 boxes in the square with a total cost of \$41.
• ...another hint ... :10 out of 25 meals would cost \$41