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Mathematics 9 Online
OpenStudy (anonymous):

Help Please! You and two friends are out running. You pass a group of five other runners. Each person in each group greets each person in the other group. How many greetings are there?

OpenStudy (anonymous):

I thought the answer would be 10 but I must've done something wrong because it wasn't.

OpenStudy (anonymous):

Never mind I figured it out. It's 20. Because 5 of the runners greet each runner which is the 2 then the 2 runners greet the 5 runners.

OpenStudy (babynini):

hmm. There are 5 people, each greeting five people. |dw:1431757247889:dw|

OpenStudy (babynini):

How many greetings is that? for this first group.

OpenStudy (anonymous):

Ahh wait it says you and 2 friends so wouldn't it be 3 runners and they pass the 5 runners?

OpenStudy (babynini):

ooh! sorry I misread the question. I thought it was five people passing 5 -.- sowiee

OpenStudy (unknownunknown):

This is just basic multiplication. Group A has 3 runners (you and 2 friends), group B has 5 runners. There are 3*5 = 15 possible combination for greeting.

OpenStudy (anonymous):

Lol it's cool but I think I see my mistake now. Thanks for your help :)

OpenStudy (anonymous):

Thank you both I appreciate the help! :D And yes now I see it would be 15.

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