Final answer:
The calculation of a new decibel level on a street when the number of cars is reduced cannot be given without applying logarithmic properties associated with sound intensity levels. Since decibel levels are on a logarithmic scale, direct proportionality does not apply, so the question can't be accurately answered without additional information on the relationship between car numbers and decibels.
Step-by-step explanation:
The question pertains to sound intensity levels, measured in decibels (dB), and how they relate to the number of cars passing on a street. While the question presents a scenario where the average decibel level of a busy street is 65 dB with 139 cars passing per minute, it then asks what the decibel level would be if the number of cars reduces to 45 per minute on a weekend, assuming sound intensity is proportional to the number of cars.
However, to calculate the new decibel level numerically after a reduction in the number of cars, we would need to apply the properties of logarithmic scales specific to sound intensity levels. These properties are not provided within the context of the question, as a direct proportionality relationship does not apply to decibels since the decibel scale is logarithmic, not linear. Therefore, without further information regarding the specifics of how decibels scale with car count, a precise numerical answer cannot be provided.
What we can say qualitatively is that if the number of cars is reduced, and each car's contribution to sound level is the same, the overall sound intensity level on the street would decrease, but not in direct proportion to the number of cars.