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Signals are made by arranging 2 flags one above the other from 4 flags of different colours. How many signals are possible?
AFour signals
BEight signals
CTen signals
DTwelve signals
Answer & Solution
Correct answer: D. Twelve signals
1. The upper position can take any of the 4 flags.
2. The lower position then has 3 flags remaining.
3. By the multiplication principle the total is 4 times 3, which is 12.
_Source: NCERT Class 11 Mathematics, Ch 6 'Permutations and Combinations'_
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