5) CEO of Spiffy Lube -- Seattle's oil change franchise wants to estimate the mean amount of time its mechanics take to complete an oil change for Spiffy Lube customers. From past reports the population standard deviation is known to equal 10 minutes. What sample size is needed if the CEO wants to be 93% confident of being within (+) 2 minutes of the true mean amount of time mechanics take to change oil? (SHOW WORK for CREDIT; write the interval boundaries to THREE decimal places; 1 point)