1. ((1001)^2 - (999)^2) / ((101)^2 - (99)^2)
1)10
2)20
3)40
4)80
5)100
2. From a group of 21 astronauts that includes 12 people with previous experience in space flight, a 3 person crew is assembled in which exactly 1 person in the crew has experience in space flight. How many different crews of this type is possible.
1)432
2)594
3)864
4)1330
5)7980
both answers are a[/spoiler]
1)10
2)20
3)40
4)80
5)100
2. From a group of 21 astronauts that includes 12 people with previous experience in space flight, a 3 person crew is assembled in which exactly 1 person in the crew has experience in space flight. How many different crews of this type is possible.
1)432
2)594
3)864
4)1330
5)7980
both answers are a[/spoiler]
