Maths statistics

QQEETIQE E: (15 marks) (a) An insurance company re-investigated the motorbike accident claims for 155 random (13) clients who claimed the insurance and found that a sample proportion of 0.85 claims are valid. Determine the 95% condence interval for the proportion of all claims are valid. (5 marks) A study was conducted to estimate the average spent on monthly data usage among university students. A random sample of 111 students were surveyed and found that the mean spent for the data usage was $55 and a standard deviation of $3. (i) Compute the standard error for the population mean. (3 marks) (ii) State the critical value, Zm2 at 99% confidence level. (1 mark) (iii) Find the reasonable range of values for the true population mean for data usage at 99% condence level. (4 marks) (iv) Interpret your answer in part (b)(iii). (2 marks)