A boat moves up and down on a lake as a wave passes by. If the boat oscillates 10 times in 2 seconds, what is the period of the wave?

The boat completes 10 oscillations in 2 seconds, so its frequency is 10 ÷ 2 = 5 oscillations per second. The period is the time for one oscillation, which is 1 ÷ 5 = 0.2 seconds, so the correct choice is 0.2 seconds.

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