Question

Total number of ways in which five ${}^{\prime }{+}^{\prime }$ and three ${}^{\prime }{-}^{\prime }$ signs can be arranged in a line such that no two ${}^{\prime }{-}^{\prime }$ sign occur together is

• A. 10
• B. 20
• C. 15
• D. None of these

Answer 1

Answer: (B)

$+++++$
On fixing five positive signs, there are $6$ places for negative signs.
$\therefore$ Required number of ways $={}^6{C}_3=20$