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counting and probability intermediate

Problem

A row of 8 light switches controls different banks of lights in a school gymnasium. In preparation for a school dance, students decide that they want either one or two banks of lights on during the dance. How many possible ways are there of setting these 8 switches so that either one or two banks of lights are on?
Solution
There are two cases here. If one bank of lights is on, there are ways to choose which bank of lights it is. If two banks of lights are on, there are ways to choose which banks of lights they are. The total number of valid settings is .
Final answer
36