Question

The number of ways in which 3 red pens, 4 blue pens and 3 black pens can be arranged in a row, if the pens of the same colour are identical

• A. 4200
• B. 25200
• C. 420
• D. none of these

Answer 1

Answer: (A)

4200

We have $3$ red, $4$ blue and $3$ black pens

If the pens of the same colour are identical then we have $3!$ ways to average

But each block can have different combinations

$\therefore$ No. of arrangements possible

$=3!\times 3!\times 4!\times 3!$

$=5184$