Given ^@7^@ flags of different colors, how many different signals can be generated, if a signal requires the use of ^@3^@ flags one below the other?
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Step by Step Explanation:
- There will be as many signals as there are ways of filling in ^@3^@ vacant places in succession by the ^@7^@ flags of different colors.
To find that we will use the fundamental principle of counting, which states,
^@“^@If an event can occur in ^@m^@ different ways, following which another event can occur in ^@n^@ different ways, then the total number of occurrence of the events in the given order is ^@m \times n^@.^@”^@
- The upper vacant place can be filled in ^@7^@ different ways by any one of the ^@7^@ flags.
The second vacant place can be filled in ^@6^@ different ways by any one of the remaining 6 different flags and so on.
|| Ways to fill
- Therefore, by the fundamental principle of counting, the number of different signals ^@= 7 \times 6 \times 5 = 210^@.
Hence, the required number of different signals is ^@210^@.