Step-by-step explanation: The sale is 30% so we have to look for 70% of $88 because that's what we're paying for. So, that would be 88 times 70/100 which ends with 61.6.
if the mean is 70 minutes, then 90 minutes is 2 standard deviations above 70. if you look at the bell curve i drew, the percent of exams that took over 90 minutes is 2.5%
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