Final answer:
Air would have the lowest average speed of sound compared to water and cement because sound travels slowest in gases and air is less dense compared to the other options.
Step-by-step explanation:
Based on the information provided, you would expect air to have the lowest average speed of sound when compared to water and cement. The speed of sound is dependent on the properties of the medium through which it is traveling. In general, sound travels slowest through gases, faster through liquids, and fastest through solids. This is because particles in solids are closely packed together, allowing sound waves to transmit their energy more efficiently. Since air is less dense than either water or cement, which are according to the data a liquid and a solid respectively, the sound waves move through it more slowly. Therefore, air has the lowest average speed of sound among the options given. Furthermore, the speed of sound is affected by temperature; in colder conditions, the speed of sound in air decreases, as indicated in the statement about a school being colder than usual.