Alex is planning to display four photographs in a line on his shelf. He has seven photographs available to choose from. How many different ways can he arrange the photographs on the shelf?

Answer Choices

Correct answer marked below

210

840

Correct

5040

504

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Explanation

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Official Explanation

Official

To find the number of arrangements for the four photographs, we can use the slot method. We have four slots to fill: _ _ _ _. The first slot can be filled with any of the 7 photographs. After placing one photograph in the first slot, there are 6…

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Comments

SuryaMar 21, 2024

This is definitely a test-day trap

AbhikNov 2, 2024

thanks!

What this question tests

What it tests

Whether you can count arrangements and selections correctly — permutations vs. combinations.

Common trap

Overcounting: treating a selection as ordered when order does not matter, or forgetting to divide by duplicates.