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Question
Four letters E, K, S and V, one in each, were purchased from a plastic warehouse. How many ordered pairs of letters, to be used as initials, can be formed from them?
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Solution
Here, we need to find out the number of pairs of the letters that can be formed with the 4 letters.
Required number of ordered pairs = Number of arrangements of four letters, taken two at a time = 4P2
\[= \frac{4!}{\left( 4 - 2 \right)!}\]
\[ = \frac{4!}{2!}\]
\[ = \frac{4 \times 3 \times 2!}{2!}\]
\[ = 4 \times 3\]
\[ = 12\]
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