SOLUTION: If there are 20 people waiting on the bus stop and you are driving your car, you stop and take with you 3 out of 20 on the bus stop (3 different people). But, it matters who sits o

Question 969829: If there are 20 people waiting on the bus stop and you are driving your car, you stop and take with you 3 out of 20 on the bus stop (3 different people). But, it matters who sits on the front seat, and for the 2 other people who will seat on the back, ordering doesn't matter. How many combinations can be ?!
Answer by AnlytcPhil(1806) (Show Source): You can put this solution on YOUR website!
If there are 20 people waiting on the bus stop and you are driving your car, you
stop and take with you 3 out of 20 on the bus stop (3 different people). But, it
matters who sits on the front seat, and for the 2 other people who will seat on
the back, ordering doesn't matter. How many combinations can be ?!

You can pick the person to sit in the front seat 20 ways.  

For each of those 20 ways when you have picked the person to ride shotgun, there are 
19 people remaining from which to pick the pair to sit in the back.  That's: 

 ways for each of those 20 way to pick the shotgun rider.

Answer:  20*171 = 20C1*19C2 = 3420 ways.  

AnlytcPhil (stands for "analytic philosophy")

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