Respuesta :
Answer:
[tex]9[/tex]
Step-by-step explanation:
GIVEN: A blue plane, a red plane and a white plane are waiting to take off from an airport that has two runways. Planes must take off from the airport one at a time, but can take off from either runway.
TO FIND: In how many ways can the three takeoffs be scheduled.
SOLUTION:
As there are two runways on airport maximum plane can take off at a time.
Now,
Total number of ways when one plane takes off at a time. [tex]=3![/tex]
[tex]=6[/tex]
Total number of ways when two plane takes off at a time = [tex]3 \choose 2[/tex]
[tex]=3[/tex]
Hence total number of ways in which three flights can be scheduled [tex]=6+3[/tex]
[tex]=9[/tex]
