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Teachers & SchoolsStatistics, Data, and Probability I: Drill Set 5, Problem 3. If the Alpha Ape randomly selects a block, what is the probability that it is not triangularly or pentagonally shaped?

CAHSEE Math | Statistics, Data, and Probability I |

Language | English Language |

Statistics and Probability | Probability |

Statistics, Data Analysis, and Probability 6 | Probability |

Their weapons are made from toy building blocks

so... the guards guffaw at their efforts.

In each set of blocks, there are:

Three triangles, two squares, two rectangles, two circles,

one pengaton -- the politically minded ape really loves that one;

and two hexagons. The witch apes love that one.

If the Alpha Ape randomly selects a block,

what is the probability that it is not triangularly or pentagonally shaped?

And here are the potential answers...

So what's this question really asking?

Well, it's a basic probability problem with one of those OR statements. And one curveball.

Notice that NOT in the question.

Not that kind of knot. This kind.

It says "what is the probability that the selected toy is NOT triangularly OR pentagonally shaped?"

The "Not" tells us that we're looking for... whatever follows it.

Also note that the NOT covers BOTH triangularly AND pentagonally shaped objects.

Think of it as looking like this:

So first we need to add up the TOTAL objects

at stake here -- as usual, that'll be the number we'll put in the denominator:

And we get: 3 plus 2 plus 2 plus 2 plus one plus 2 for a total of 12 items.

So 12 is the denominator.

In the numerator we have whatever the total

of triangularly and pentagonally shaped items is --

and that's the quantity 3 plus 1 or 4.

So we have 4 out of 12 as the odds of selecting

a triangular or pentagonally shaped item.

But ding ding ding -- this is the OPPOSITE of what the question is asking.

It wants everything BUT those ape...

It wants everything BUT those shapes...

So the right answer is 12 MINUS that number or 8 and we get 8 over 12 as the odds of NOT

selecting the triangular or pentagonally shaped weapons -- er um -- items from the box.

And after going on a quick crash diet, our fraction reduces to 2 over 3.

Thank you Jenny Craig.

Or answer B.

Before the Alpha Ape even has a chance to go block diving...

...the zookeeper arrives.

World domination will have to wait.

It's banana time. They have appeal.