Engineering Board Exam Reviewer · Permutations · medium

In how many ways can 6 people be arranged in a row if person A must stand somewhere to the left of person B?

  1. 120
  2. 360
  3. 240
  4. 720

Answer

B. 360

Solution

Of the 6!=720 arrangements, exactly half have A to the left of B by symmetry: 720/2=360.

More Permutations questions

  1. In how many ways can 3 boys and 3 girls be arranged in a row so that boys and girls alternate?
  2. In how many ways can the letters of the word COMPUTER be arranged so that the three vowels are together?
  3. How many 4-digit numbers can be formed from the digits 0 to 9 if no digit is repeated?
  4. How many distinct arrangements can be made from the letters of the word ENGINEER?
  5. How many distinct arrangements can be made from the letters of the word BANANA?
  6. In how many ways can 7 different books be arranged on a shelf?
  7. Eight contestants compete. In how many ways can first, second, and third place be awarded?
  8. In how many ways can 6 different books be arranged on a shelf?
  9. How many ways can a president, vice president, and secretary be chosen from a club of 10 members (distinct roles)?
  10. In how many ways can the letters of the word "NUMBER" be arranged?

All Permutations questions