Find the number of different signals that can be generated by arranging at least 222 flags in order(one below the other) on a vertical staff, if 555 different flags are available.


Answer:

320320320

Step by Step Explanation:
  1. A signal can consist of either 222 flags, 333 flags, 444 flags or 555 flags. Now, let us count the possible number of signals consisting of 222 flags, 333 flags, 444 flags, and 555 flags separately and then add the respective numbers.
  2. There will be as many 222 flag signals as there are ways of filling in 222 vacant places in succession by the 555 flags available.
    By the fundamental principle of counting, the number of ways is 5×4=205×4=205×4=20
  3. Similarly, the number of 3 flag signals is 5×4×3=605×4×3=605×4×3=60, the number of 444 flags signals is 120120120 and the number of 555 flags signals is 120120120.
  4. Therefore, the required no. of signals =20+60+120+120=20+60+120+120=20+60+120+120=320.=320.=320.

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