The loudness l(x) measured in decibels, of a sound of intensity x, measured in watts per square meter, is defined as l(x)=10 log (x/i base 0=10^-12 watt per square meter is the least intense sound that a human ear can detect. determin the loudness, in decibels, of each following sounds. 1. diesel truck traveling 40 miles per hour 50 feet awar: intensity 10 times that of a passenger car traveling 50 miles per hour 50 feet away whose loudness is 70 decibels

If you can find your way through all the smoke of the definition,
you find that an increase of 10 times the intensity is an increase
of 10 dB.

Next, if you can find your way over, under, around, and through
all the speeds and distances of the vehicles, you'll find that you
don't need them.  Right in the middle of the pile, it says "intensity
10 times that of ...".  That right there tells you that the sound of
the truck is 10 dB louder than the sound of the car.

So the car is 70 dB (asked for, and then given), and the truck is 80 dB.