Problems 131–134 use the following discussion: The loudness L(x), measured in decibels (dB), of a sound of intensity x, measured in watts per square meter, is defined as L(x) = 10 log x/I₀, where I₀ = 10⁻¹² watt per square meter is the least intense sound that a human ear can detect. Determine the loudness, in decibels, of each of the following sounds.

Diesel truck traveling 40 miles per hour 50 feet away: intensity 10 times that of a passenger car traveling 50 miles per hour 50 feet away, whose loudness is 70 decibels.