Error in solving for raw score; incorrect formula used? _According to a study of how long a person is willing to wait for their flight, it is found that the mean time a person is willing to wait is 5.2 hours with a standard deviation of 1.1 hours._ _Consider the 20% of people who are least willing to spend time traveling. How many hours traveling is the cut-off at which these people would not consider waiting?_ This practice question asks me of the formula used, as well as the answer. The formula I am using (which is confirmed via answer key) is: $$x = z\sigma + \mu$$ $$x = (0.2*1.1)+5.2$$ $$x = 5.42$$ However, the answer provided does not match, with a hard $x = 4.276$. I'm not entirely sure why this is the answer despite using the same formula it indicates to use.

You want the $z$ such that $Pr(Z
$$ x=(-0.84)*1.1+5.2=-0.924+5.2=4.276. $$