A student is planning for his final year project sample size for determining the electricity consumption for a dryer. The electricity consumption is assuming to be normally distributed with standard deviation of 150 kW. How large sample must be selected if he wants 98% of finding whether the true mean differ from the sample mean by 50kW.
(a) A student is planning for his final year project sample size for determining the electricity consumption for a dryer. The electricity consumption is assuming to be
(b) A researcher wants to compare the effect of several method on gold plating. For the first method, the printed circuit edge connecters were gold plated with control immersion tip plating. While for the second method, it was plated with total immersion plating before it was masked. 7 printed circuit edge connectors were chosen for the first method and five connectors were masked in the second method, had mean of gold thickness was 1.5 um and 1.0 μm, respectively. For standard deviation, both samples have 0.25 um and 0.15 um, respectively. Construct a 99% confidence interval for the difference between the mean of gold thicknesses produced by the two methods.
(c) A researcher wishes to claim that the average final examination mark of Manufacturing Technology is different than 80. He selects a sample of 25 students and find the mean of the sample is 79, with a standard deviation of 4 marks. Is there any evidence to support this claim, if a = 0.1.
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