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Cogito

Grade 7 Math · Chapter 9 · Lesson 3

Practice Worksheet

Probability as a Number

Nought means never, one means always.

10 problems · about 18 minutes · 7.SP.C.5

NameDate

Figure — use these to answer the problems

The outcomes you want, against the ones you do not.
favourable and the rest
all outcomes
Outcomes you want1
The other outcomes5
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

3 problems

  1. From “Samples and What They Tell You”

    9 of 30 sampled. In 300, about how many?

    Answer

  2. From “Probability as a Number”

    A fair die. Out of 6, how many outcomes are less than 3?

    Answer

  3. From “When Three Measurements Fix a Triangle”

    Can sides 4, 4 and 9 make a triangle? 1 for yes, 0 for no.

    Answer

Warm Up

Straightforward practice. Get the method working first.

3 problems

  1. A die. How many outcomes give a number above 4?

    Answer

  2. A die. How many outcomes give an even number?

    Answer

  3. A die. How many outcomes in total?

    Answer

Build It Up

The same ideas with more to keep track of.

2 problems

  1. What is the probability of a certain event?

    Answer

  2. 4 green out of 10. How many are not green?

    Answer

Stretch Yourself

Mixed problems. Work out what kind of question it is before you start.

2 problems

  1. The Bag

    2 red and 8 blue. Out of 10, how many outcomes are red?

    Answer

  2. The Certainty

    What is the probability of an impossible event?

    Answer