Complete the passage to summarize factors affecting the speed of a wave.
The material or substance that a wave moves through is called a
The medium affects the spee
of the wave that passes through it. One factor that affects the speed of a wave is the
of medium.
Some waves move faster in solids and some waves move faster in liquids and gases. Another factor that affects
wave speed is the
of the medium.

Researchers conducted an experiment to identify the effects of three different hand sanitizers on the growth of bacteria. the researchers grew one type of bacteria in twenty-four identical covered petri dishes. then, they opened eighteen petri dishes and applied the three hand sanitizers to six petri dishes each. they left the remaining six petri dishes closed as a control group. when the researchers measured the growth of bacteria two days later, the six dishes that had no hand sanitizer showed the least amount of bacterial growth. the researchers concluded that not using any hand sanitizer would lead to the least bacterial growth. which statement best explains why the researchers’ conclusion was not justified? the experiment tested too many variables. the control group was not treated the same as the experimental group. the sample size of twenty-four petri dishes is not large enough. the single type of bacteria is not adequate to make any conclusions.