The diameter of a spindle in a small motor is supposed to be 4.6 millimeters (mm) with a standard deviation of 0.11 mm. If the spindle is either too small or too large, the motor will not work properly. The manufacturer measures the diameter in a sample of 10 spindles to determine whether the mean diameter has
For each situation, state the null and alternative hypotheses: (Type "mu" for the symbol ?μ , e.g. mu >> 1 for the
(a) The diameter of a spindle in a small motor is supposed to be 4.6 millimeters (mm) with a standard deviation of 0.11 mm. If the spindle is either too small or too large, the motor will not work properly. The manufacturer measures the diameter in a sample of 10 spindles to determine whether the mean diameter has moved away from the required measurement. Suppose the sample has an average diameter of 4.73 mm.
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(b) Harry thinks that prices in Caldwell are higher than the rest of the country. He reads that the nationwide average price of a certain brand of laundry detergent is $16.85 with standard deviation $1.15. He takes a sample from 3 local Caldwell stores and finds the average price for this same brand of detergent is $15.67.
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