The headphones are $80.99 and are 35% off. To find the amount he will save, change the 35% to a decimal by moving it two times to the left, which is 0.35. Multiply 80.99 and 0.35 to get 28.3465. Round to get $28.35.
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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