Papa Fred's Pizza has found that the menu time to deliver a pizza is 21.2 minutes with a
standard deviation of 6.1 minutes. They want to have a guaranteed delivery time. In order to
deliver 99% within the guaranteed time you need to find the time represented by the 99
percentile. What is this value?

That time is  35.4 minutes.

Step-by-step explanation:

The mean time of delivery follows a Normal Distribution pattern.

So we need to apply Z-scores to find out.

99% confidence  in delivery time means  P(z > value) = 0.01  = 1%

So    z > 2.325

so.      Pr [ (x - 21.2) /  6.1   >  2.325 ] = 1%

so  x  >  2.325*6.1 + 21.2

x  >  35.3825 minutes  would be out of the 99th percentile

do you mean add both of the equations together

because if you do the answer is 10x-5

step-by-step explanation:

because linear equations are a lot simpler than quadratics equations, and linear equations formula is a lot easier to memorize. that's why i think they're harder.