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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?
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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