Two civil engineers are arguing about the tensile strength o

Two civil engineers are arguing about the tensile strength of spider silk. Ann is convinced the tensile strength is 1000 MPa, while Bob is certain it is 1100 MPa. Fortunately both of them agree the standard deviation is 200 Mpa. To settle the argument Ann decides to take 40 random strands of spider silk and test the average strength. She will test with =0.01 whether the spider silk is significantly larger than 1000. Bob is frustrated because he thinks her test does not have the power to show her average is wrong. Calculate the power for Bob.

Xcritical = 1073, power = 0.7967

Solution