Six different machines are being considered for use in manufacturing rubber seals. The machines are being compared with respect to tensile strength of the product. A random sample of four seals from each machine is used to determine whether the mean tensile strength varies from machine to machine. The following are the tensile-strength measurements in kilograms per square centimeter x 10-1: Machine 3 4 16.4 20.3 14.6 17.5 2 6 18.3 17.5 16.9 19.2 15.7 16.7 19.2 16.2 15.8 17.7 17.8 20.8 16.5 17.5 18.6 15.4 18.9 18.9 20.5 20.1 Perform the analysis of variance at the 0.05 level of significance and indicate whether or not the mean tensile strengths differ significantly for the six machines.

Trace metals in drinking water affect the flavor and an unusually high concentration can pose a health hazard. Ten pairs of data were taken measuring zinc concentration in bottom water and surface water. Bottom 0.430 0.266 0.567 0.531 0.707 0.716 0.651 0.589 0.469 0.723 Surface 0.415 0.238 0.390 0.410 0.605 0.609 0.632 0.523 0.411 0.612 Does the data suggest that the true average concentration in the bottom water is different than that of surface water? Note: You can assume that the conditions for inference are met.

Several methods of estimating the number of seeds in soil samples have been developed by ecologists. An article gave the accompanying data on the number of seeds detected by the direct method and by the stratified method for 27 soil specimens. Specimen 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Direct 21 33 0 60 20 61 40 8 13 93 1 68 77 21 Stratified 8 37 8 57 53 61 28 8 8 100 0 57 68 53 Specimen 15 Find the test statistic. (Round your answer to two decimal places.) t = 16 17 18 19 20 21 22 23 24 25 26 27 Direct Find the df. (Round your answer down to the nearest whole number.) df = 33 0 37 17 93 1 40 21 0 8 13 Use technology to find the P-value. (Round your answer to four decimal places.) P-value = 17 40 Stratified 28 0 37 13 93 13 48 21 0 13 40 Do the data provide sufficient evidence to conclude that the mean number of seeds detected differs for the two methods? Test the relevant hypotheses using a = 0.05. (Use direct stratified.) 13 77

Given the population: {0, 1, 2, 3, 4}, calculate the mean. Ομ3.0 Ομ2.5 I = 2.0 Ομ2.0

Values of modulus of elasticity (MOE, the ratio of stress, i.e., force per unit area, to strain, i.e., deformation per unit length, in GPa) and flexural strength (a measure of the ability to resist failure in bending, in MPa) were determined for a sample of concrete beams of a certain type, resulting in the following data: MOE 29.7 33.1 33.6 35.2 35.4 36.2 36.2 36.3 37.4 37.8 Strength 5.8 7.1 7.2 6.2 8.0 6.9 7.1 7.7 6.7 6.4 MOE 38.6 38.7 39.7 40.9 42.7 42.7 43.6 45.7 45.9 46.8 Strength 7.1 6.4 8.0 8.9 8.3 8.8 7.9 9.6 7.3 7.6 MOE 47.9 49.2 51.6 62.7 69.7 79.6 80.1 Strength 9.8 7.7 7.8 11.5 11.4 11.9 10.6 Fitting the simple linear regression model to then = 27 observations on x = modulus of elasticity and y = flexural strength given in the data above resulted in ý = 7.589, s, = 0.180 when x = 40 and ý = 9.749, s, = 0.255 for x = 60. The simple linear regression model also resulted in a value of s = 0.8718.