There are three identical red balls and fouridentical blue balls in a bag. Three balls are down. The number of different colour combination is
A. | 20 |
B. | 35 |
C. | 40 |
D. | 30 |
Option: D Explanation : Click on Discuss to view users comments. |
How many five different letter words can be formed out ofthe word "LOGARITHMS"?
A. | 20120 |
B. | 30120 |
C. | 30240 |
D. | 40840 |
Option: C Explanation :
Total letters in the word "LOGARITHMS" is 10,i.e. n=10 and we have to form five-letter words
= 10 x 9 x 8 x 7 x 6 = 30240 Click on Discuss to view users comments. |
Given np_{r} = 3024
Value of r will be
A. | 3 |
B. | 4 |
C. | 6 |
D. | 9 |
Option: B Explanation : Since ^{n}p_{r} is product of consecutive positive integers. ^{n}p_{r} = 3024 = 9 x 8 x 7 x 6 Hence, r = 4 Click on Discuss to view users comments. |
A. | 20 |
B. | 30 |
C. | 60 |
D. | 120 |
Option: C Explanation : First three jobs can be filled by 5 members in ^{5}P_{3} ways. Number of ways of filling the first 3 jobs
^{5}P_{3 }= 5 x 4 x 3 = 60 ways
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