Bunuel Can you or someone please help what I am missing in this approach?
(
Note that while each couple is required to order the same dessert, this dessert does not need to match the one ordered by the other couples.)
1st couple can choose any desert out of 9 deserts available.
2nd couple can choose among the remaining
8 deserts available . ( 1 desert has already been picked up by the 1st couple)
3rd couple can choose among the remaining
7 desert available .( 2 deserts have already been picked by 1st and 2nd couple).
Total ways in which the husband and wife of each couple will order the same dessert= 9*8*7 (no repetition as the deserts does not need to match the one ordered by the other couples).
Every person in the group out of 6 people(3 couples) can order 9 deserts.
Total no. of ways to order desert = 9^6
So required Probability = (\(\frac{9*8*7}{9^6}\)).
Note that while each couple is required to order the same dessert, this dessert does not need to match the one ordered by the other couples.
The above means that all three couples, or two of the three, can select the same desert.