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8th grade Chance of "this or that": overlapping and mutually exclusive events worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

Level: Building Confidence · On Level · Challenge Me

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Chance of "this or that": overlapping and mutually exclusive events

Grade 8 Math Worksheet - Building Confidence

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Circle the best answer, or write your answer on the line.

  1. Bo's spinner has 10 equal sections, and 4 are blue. Bo picks one at random. In simplest form, what is the chance it is NOT that kind?

  2. Esme mixes 12 cards, and 5 of them have a star (the rest have a moon). Esme picks one at random. In simplest form, what is the chance it is NOT that kind?

  3. Jun rolls a number cube. Which list shows every outcome for 'an even number'?

    • 2, 4
    • 1, 3, 5
    • 2, 4, 6
  4. Kira rolls a fair number cube. What is the chance of a 5 or a 6?

    • 1/3
    • 1/36
    • 1/6
  5. Luz picks one card at random from cards 1 to 10. What is the chance of a 3 or an 8?

    • 1/5
    • 1/10
    • 1/100
  6. The forecast gives Milo's town a 0.3 chance of rain. What is the chance of no rain?

    • 0.7
    • 0.3
    • 1.3
  7. Noah adds the chance of an event and the chance of its opposite. What is the total?

    • 1/2
    • 1
    • 0
  8. What is the opposite of 'rolling a 6' on Pia's number cube?

    • Rolling a 6 again
    • Rolling 1, 2, 3, 4 or 5
    • Rolling a 1
  9. Which pair of events cannot happen on the same roll of Ren's number cube?

    • Rolling a 1 and rolling a 6
    • Rolling an even and rolling a 4
    • Rolling under 3 and rolling a 2
  10. Tala pulls one sock, and each sock is one color. Can that sock be both red and blue?

    • Yes, if the chances add up
    • Yes, half of the time
    • No, one sock has one color
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8th grade Chance of "this or that": overlapping and mutually exclusive events worksheet – printable
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About this worksheet

Find the chance of an event, its opposite, and 'this or that' for events that do or do not overlap. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can find the chance an event does NOT happen as 1 minus its chance.
  • I can tell whether two events can happen on the same try.
  • I can add the chances of two events that cannot happen together.
  • I can find the chance of A or B for overlapping events by taking the overlap away once.

Standard: IXL parity (Nov 11) (nearest: 7.SP.C.8; S-CP.B.7 in Algebra 2)

Words to know

outcome: One possible result, like rolling a 4

event: A set of outcomes, like rolling an even number

opposite (complement): Every outcome the event leaves out

cannot happen together (mutually exclusive): Two events that share no outcome

overlap: Outcomes that are in both events

Common mistakes

Your child gave the chance of the event itself. The question asked for the opposite, so take the event's chance away from 1.

Your child multiplied the two chances. Multiplying is for 'this and then that'; for one pick that is 'this or that', add the chances.

Your child added the two groups but counted the outcomes in both groups twice. Add the groups, then take the overlap away once.

Questions parents ask

What is the most common mistake with chance of "this or that": overlapping and mutually exclusive events?

Your child gave the chance of the event itself. The question asked for the opposite, so take the event's chance away from 1.

Are these 8th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

More grade 8 math

See all grade 8 math

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