Estimate the 95% confidence interval for the time it takes for typical salary earning taxpayers to complete their tax return using eFiling.
SARS (the South African Revenue Service) believes that it takes typical salary-earning taxpayers less time on average, to complete their tax return using eFiling (the online tax return submission system). SARS randomly selected 12 salary-earning taxpayers who had registered for eFiling, and recorded their time to complete the eFiling process. The completion times (in minutes) for the sample of 12 taxpayers are given in the table below:
42 56 29 35 47 37 39 29 45 35 51 55 Estimate the 95% confidence interval for the time it takes for typical salary earning taxpayers to complete their tax return using eFiling.
3. A national bank analysed a random sample of 365 cheque accounts at their Durban branch and found that 78 of them were overdrawn. Estimate, with 92% confidence, the percentage of all bank accounts at the Tshwane branch of the bank that were not overdrawn. Interpret the findings.
4. If �bar = 85, σ = 8 and n = 64, set up a 97% confidence
5. Suppose the response time X at a certain on-line computer terminal (the elapsed time between the end of a user’s inquiry and the beginning of the system’s response to that inquiry) has an exponential distribution with expected response time equal to 2 seconds.
a. Compute lambda. b. What is the probability that the response time is at most 10 seconds?
c. What is the probability that the response time is between 5 and 10 seconds?
d. Compute the variance of this distribution.
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