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

Answer Key - Grade 8 Math Worksheet - Building Confidence

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

1. 1.

   Ari's bag holds 8 counters, and 3 of them are red. Ari picks one at random. In simplest form, what is the chance it is NOT that kind?

   5/8
2. 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?

   7/12
3. 3.

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

   • 2, 4
   • 1, 3, 5
   • 2, 4, 6
4. 4.

   Kira rolls a fair number cube. What is the chance of a 5 or a 6?

   • 1/6
   • 1/3
   • 1/36
5. 5.

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

   • 1/5
   • 1/100
   • 1/10
6. 6.

   The forecast gives Milo's town a 0.3 chance of rain. What is the chance of no rain?

   • 0.7
   • 1.3
   • 0.3
7. 7.

   Noah adds the chance of an event and the chance of its opposite. What is the total?

   • 1
   • 0
   • 1/2
8. 8.

   What is the opposite of 'rolling a 6' on Pia's number cube?

   • Rolling a 1
   • Rolling 1, 2, 3, 4 or 5
   • Rolling a 6 again
9. 9.

   Which pair of events cannot happen on the same roll of Ren's number cube?

   • Rolling a 1 and rolling a 6
   • Rolling under 3 and rolling a 2
   • Rolling an even and rolling a 4
10. 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
    • No, one sock has one color
    • Yes, half of the time