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QUESTION 16 A random sample of 34 students at ZU showed an average age of 25 years and a standard deviation of 2 years. Which distribution should we use to construct the 98% condence interval for the mean age of all ZU students? 0 Standard normal distribution 0 t-distribution with 33 degrees of freedom 0 Neither t nor standard normal distribution. 0 t-distribution with 34 degrees of freedom QUESTION 17 Majed computed a 95% condence interval for the average time (in minutes) spent on social networking daily by college students in UAE as (102, 128). Given that the size of the sample is 43, nd the sample standard deviation. Round your answer to two decimal places. QUESTION 18 The time customers spent waiting to be served in a restaurant is assumed to be normally distributed with a mean of 8.4 minutes and a standard deviation of 1.29 minutes. 25 customers are randomly selected. There is only 5% chance that the average wainting time is greater than which value? Round your answer to three decimal places. QUESTION 19 The lifespan of a certain light bulb is normally distributed with a mean of 400 hours and a standard deviation of 12 hours. If 36 light bulbs are randomly selected, nd the probability that their average lifespan will be between 395 hours and 405 hours. Round your answer to four decimal places