The article "influence of penetration rate on penetrometer resistance" (j. oliveira, m. almeida, et al., journal of geotechnical and geoenvironmental engineering, 2011: 695â703) presents measures of navidi-3810214 book november 11, 2013 14: 8 446 chapter 6 hypothesis testing penetration resistance, expressed as a multiple of a standard quantity, for a certain fine-grained soil. fifteen measurements taken at a depth of 1 m had a mean of 2.31 with a standard deviation of 0.89. fifteen measurements taken at a depth of 2 m had a mean of 2.80 with a standard deviation of 1.10. can you conclude that the penetration resistance differs between the two depths?