Independent samples

1. A manufacturer has accumulated the following information from its two factories

	Daily defects in Sydney	Daily defects in Melbourne
Sample mean	4000	4300
Sample standard deviation	100	70
Sample size	100	100

The manager of the Melbourne factory claims there is no significant difference in the
number of defects in the two factories. Test the manager’s claim at 1% level of
significance (assume that the population are normally distributed and have equal variances).

2. Referring to the above table, what is the estimated standard error of the difference between the two sample means? (Assume that the two population variances are equal)

3.Given the following information on two independent samples calculate a 95% confidence interval. Assume the populations have equal variances