Final answer:
Option d) 75000 Hz is the correct answer, as 75 thousand repeats or cycles per second equate to a frequency of 75000 Hz. Frequency is measured in Hertz (Hz) and represents the number of cycles occurring each second.
Step-by-step explanation:
75 thousand repeats equal how many Hz is option d) 75000 Hz. 'Repeats' in this context is assumed to mean cycles or oscillations per second, which is the definition of Hertz (Hz). Therefore, 75 thousand cycles per second are exactly 75000 Hz.
The term 'frequency' refers to how often something happens per second and is measured in Hertz (Hz). The frequency of a wave is inversely related to its period, which is the duration of time for one complete cycle to occur. A higher frequency means more cycles per second, while a lower frequency means fewer cycles per second. For instance, a frequency of 10 Hz has a period of 0.1 seconds, as indicated by the formula period (T) = 1 / frequency (f).
Additionally, the ability of humans to distinguish between two separate sounds, known as the smallest frequency difference distinguishable or just noticeable difference, is generally around 1 to 3 Hz for low frequencies and can be around 100 Hz or more for higher frequencies.