Question

The number of ways in which 10 persons can go in two boats so that there may be 5 on each boat, supposing that two particular persons will not go in the same boat is_______.

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

First omit two particular persons; remaining 8 persons may be 4 in each boat. This can be done in $8C_4$ ways. The two particular persons may be placed in two ways one in each boat. Therefore total numbers of ways are = $2\times 8C_4$.