10) It is known that for = 0.1, z_/2= 1.645. Using this fact, solve the following problem. A sample of 68 companies was taken to find out how many companies went bankrupt over the period of 10 years. The proportion of the companies which filed bankruptsy appeared to be 0.14 in the sample. What is the left boundary of 90% confidence interval to estimate the proportion of bankrupt companies over the period of 10 years? Assume that the conditions for the samling distribution to be approximately normal are satisfied. Round your answer to 4 decimals.

11) To test the reliability of electric devices, a sample of 35 devices was taken. The mean number of minutes that the devices in the sample performed without errors was 209. The sample standard deviation was 10.9. What was the left boundary of 93% confidence interval to estimate the population mean? Use Excel for all computations and round your final answer to 2 decimals.