56. If 6 men plough a field in 10 hours, how many hours will it take 4 men to do the same work? (Assuming they are working at the same rate).
A 8 B. 15 C. 20 D. 25 E. 27

Adecibel is a logarithmic unit that can be used to measure the intensity of a sound. the function y = 10logx gives the intensity of a sound in decibels, where x is the ratio of the intensity of the sound to a reference intensity. the reference intensity is generally set at the threshold of hearing. use the graphing utility to graph the decibel function.a whisper has a sound intensity of 30 decibels. use your graph to you complete the following statement. the sound intensity of a whisper is times the reference intensity.