Free Practice Question
PS · Problem Solving
505-555
Combinations
A traffic light features 5 colors: Red, Blue, Green, Yellow, and Orange. If signals are created by selecting any of these colors, how many distinct signals can the traffic light display if the sequence of colors matters?
Answer Choices
Correct answer marked belowA
10
B
30
60
Correct
D
120
E
240
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Explanation
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Official Explanation
Official
To determine the number of unique signals, we first select 3 colors from the 5 available colors: Red, Blue, Green, Yellow, and Orange. The number of ways to choose 3 colors from 5 is given by…
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Comments
2
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D
DharunAug 27, 2024
this pattern comes up frequently
S
sawaiFeb 17, 2024
Thank for sharing!
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.
Details
Difficulty
505-555
Type
PS
Category