Engineering Maths - Permutation And Combinations

21. In a factory for five jobs the members A, B, C, D, E are eligible.

In how many ways the first two jobs can be filled?

  • Option : A
  • Explanation : First job can be filled in 5 ways by anyone of the five numbers. Out of the five, if one is selected for the first job, then second job can be filled by the remaining 4 members in 4 ways. Hence number of ways of filling the first and second jobs = 5 x 4 = 20
Cancel reply
Cancel reply

22. In a factory for five jobs the member's A, B, C, D, E are eligible. All jobs can be filled in how many ways?

  • Option : D
  • Explanation : 5 jobs can be filled by 5 members in  5Pways.
     5P5 = 5 ! = 5 x 4 x 3 x 2 x 1 
    = 120 ways.
Cancel reply
Cancel reply

24. There are four bus lines between A and B, and three bus lines between B and C.The number of ways a person can travel by bus from A to C by way of B will be

  • Option : B
  • Explanation : There are four ways to go from A to B and three ways to go from B to C, Hence there are 4 / 3 = 12 ways to go from A to C by way of R
Cancel reply
Cancel reply