Problem: The just-noticeable difference (jnd) (the threshold at which a change is perceived) depends on the tone's frequency content. Below 500 Hz, the jnd is about 3 Hz for sine waves, and 1 Hz for complex tones; above 1000 Hz, the jnd for sine waves is about 0.6% (about 10 cents). The jnd is typically tested by playing two tones in quick succession with the listener asked if there was a difference in their pitches. The jnd becomes smaller if the two tones are played simultaneously as the listener is then able to discern beat frequencies. The total number of perceptible pitch steps in the range of human hearing is about 1,400; the total number of notes in the equal-tempered scale, from 16 to 16,000 Hz, is 120.
What is the range of perceptible pitch steps to human hearing?
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Answer: 1,400

Problem: In the context of trademarks, this expansion has been driven by international efforts to harmonise the definition of "trademark", as exemplified by the Agreement on Trade-Related Aspects of Intellectual Property Rights ratified in 1994, which formalized regulations for IP rights that had been handled by common law, or not at all, in member states. Pursuant to TRIPs, any sign which is "capable of distinguishing" the products or services of one business from the products or services of another business is capable of constituting a trademark.
What is a sign that is often shared between one business and another?
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Answer: unanswerable

Problem: Luminous efficacy of a light source may be defined in two ways. The radiant luminous efficacy (LER) is the ratio of the visible light flux emitted (the luminous flux) to the total power radiated over all wavelengths. The source luminous efficacy (LES) is the ratio of the visible light flux emitted (the luminous flux) to the total power input to the source, such as a lamp. Visible light is measured in lumens, a unit which is defined in part by the differing sensitivity of the human eye to different wavelengths of light. Not all wavelengths of visible electromagnetic energy are equally effective at stimulating the human eye; the luminous efficacy of radiant energy (LER) is a measure of how well the distribution of energy matches the perception of the eye. The units of luminous efficacy are "lumens per watt" (lpw). The maximum LER possible is 683 lm/W for monochromatic green light at 555 nanometers wavelength, the peak sensitivity of the human eye.
What is not the ratio of the visible light flux emitted to the total power input to the source?
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Answer:
unanswerable