1.41 )A simple random sample of 50 ball-bearings, taken from a large population, has mean weight of 1.5 kg/bearing and standard deviation of 0.1 kg/bearing. 1.35 Two firms A and B manufacture similar components with a mean breaking strength of 3,000 (i) Estimate the standard error of mean. V and 2500 N and standard deviations of 200 N and 100 N, respectively. If random samples (ii) If the sample is taken from a production run of 150, estimate the standard error of mean. 11.39 th m h measuring reaction time, a psychologist estimates that the standard duration is 0.05 sec- of 100 components of Firm A and 50 components of Firm B are tested, what is the probabil- ond. How large a sample of measurements must be taken in order to be 95% confident that (ifi) If 10% of the bearings are known to be defective, calculate the standard error of propor- ity that the components from Firm A will have a mean breaking strength which is at least (a) the error of his estimate will not exceed 0.01 second? tions in a sample of 50. (iv) If 10% of the bearings are known to be defective, and the production run of 150 is 450 N: (b) 575 N more than the components of Firm B? considered, calculate the standard error of proportions in a sample of 50