# Engineering Maths - Combinatories

>>>>>>>>Combinatories

• A

(2n+2) !  • B

(2n+2) ! x 2  • C

(n+1) ! x 2  • D

2[(n+1) ! ]2  • A

486000  • B

468000  • C

498000  • D

489000  • Option : B
• Explanation : n = 26 x 25 x 10 x 9 x 8=468000. i.e. there are twenty-six choices for the first letter, but only twenty-five choices for the second letter which must be different from the first letter. Similarly, choices for the digits are 10, 9 and 8 since the digits must be distinct.

• A

608000  • B

608200  • C

608400  • D

608600  • Option : C
• Explanation : Each letter can be printed in twenty-six different ways, the first digit in nine ways and each of the other two digits in ten ways. Hence 26 x 26 x 9 x 10 x 10 = 608400 different plates can be printed.

Common data  for next 2 questions

Given : npr = 3024.

• A

3  • B

4  • C

6  • D

9  • Option : D
• Explanation : Since np is product of consecutive positive integers, npr=3024=9x8x7x6 Hence n=9 and r = 4

• A

3  • B

4  • C

6  • D

9  • Option : B
• Explanation : Since np is product of consecutive positive integers, npr=3024=9x8x7x6 Hence n=9 and r = 4
Related Quiz.
Combinatories