The foreman at an assembly plant is concerned that the number of defective items produced on the night shift seems to be higher than during the day shift. A random sample of 45 night shifts had an average of 35.4 defects, with a standard deviation of 15.3. A random sample of 50 day shifts had an average of 27.8 defects, with a standard deviation of 7.9.Is there sufficient evidence, at the 5% significance level, to indicate that the number of defects is higher on the night shift than on the day shift? You may assume that the population distributions of errors are normally distributed.
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