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Cogito

Probability and Statistics · Chapter 3 · Lesson 1

Practice Worksheet

Probability Basics

Measuring how likely something is.

12 problems · about 20 minutes · TEKS P.S.2.A, S-CP.A.1

NameDate

Figure — use these to answer the problems

Change the counts of each colour. The probability of drawing one is its count over the total.
Red3
Blue5
Green2
Red3
Blue5
Green2
Figure 1

Warm Up

Straightforward practice. Get the method working first.

5 problems

  1. P(A) = 0.45. What is P(not A)?

    Answer

  2. After four heads, what is the chance of heads next?

    • Still one half; the coin has no memory.
    • Less than half, since tails is due.

  3. One die. Probability of a six, as a decimal to three places?

    Answer

  4. One die. Probability of an even number, as a decimal?

    Answer

  5. P(A) = 0.2. What is P(not A)?

    Answer

Build It Up

The same ideas with more to keep track of.

3 problems

  1. A bag has 4 red and 6 blue. Probability of blue, as a decimal?

    Answer

  2. 20 trials gave 13 successes. Experimental probability, as a decimal?

    Answer

  3. Five heads in a row. Probability the next toss is tails, as a decimal?

    Answer

Stretch Yourself

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

4 problems

  1. Sort each probability by what it describes.

    Write each item under the heading it belongs to: One in six for a die, by counting faces · Half for a coin, by counting sides · 13 heads in 20 actual tosses · 47 sixes in 300 actual rolls

    Theoretical

    Experimental

  2. What is the probability of an impossible event?

    Answer

  3. The Bag

    A bag has 3 red and 7 blue marbles. What is the probability of red, as a decimal?

    Answer

  4. The Complement

    The probability of rain is 0.35. What is the probability of no rain?

    Answer