IXL | Compound events: find the number of sums

You roll a die, spin the spinner, and find the sum. How many different sums are possible?

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question

You pick one card from each set and find the sum. How many different sums are possible?

key idea

The branches of a tree diagram represent all possible outcomes.

solution

Make a tree diagram, then find the sum on each branch.

The first event has 3 outcomes: 5, 6, and 7.

The second event has 7 outcomes: 2, 3, 4, 5, 6, 7, and 8.

Make a tree diagram:

5672345678234567823456785 + 2 = 75 + 3 = 85 + 4 = 95 + 5 = 105 + 6 = 115 + 7 = 125 + 8 = 136 + 2 = 86 + 3 = 96 + 4 = 106 + 5 = 116 + 6 = 126 + 7 = 136 + 8 = 147 + 2 = 97 + 3 = 107 + 4 = 117 + 5 = 127 + 6 = 137 + 7 = 147 + 8 = 15

Look at the sum on each branch. The possible sums are all the numbers between 7 and 15, so there are 9 possible sums.

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JJ.6Compound events: find the number of outcomes

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