Permutation and CombinationHard
Question
Passengers are to travel by a double decked bus which can accommodate 13 in the upper deck and 7 in the lower deck. The number of ways that they can be divided if 5 refuse to sit in the upper deck and 8 refuse to sit in the lower deck, is
Options
A.25
B.21
C.18
D.15
Solution
upperdeck - 13 seats → 8 in upper deck.
lowerdeck - 7 seats → 5 in lower deck
Remains passengers = 7
Now Remains 5 seats in upper deck and 2 seats
in lower deck
for upper deck number of ways = 7C5
for lower deck number of ways = 2C2
So total number of ways = 7C5 × 2C2 =
= 21
lowerdeck - 7 seats → 5 in lower deck
Remains passengers = 7
Now Remains 5 seats in upper deck and 2 seats
in lower deck
for upper deck number of ways = 7C5
for lower deck number of ways = 2C2
So total number of ways = 7C5 × 2C2 =
= 21Create a free account to view solution
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