At a fixed operating setting, the pressure in a line downstream of a reciprocating compressor has a mean value of 12.0 bar with a standard deviation of 1.0 bar based on a very large data set obtained from continuous monitoring. Required:
What is the probability that the line pressure will exceed 13.0 bar during any measurement?

P [ Z > 13 ] = 0,1587       or       P [ Z > 13 ] = 15,87 %

Step-by-step explanation:

The probability that the line pressure will exceed 13.0 bar is:

P [ Z > 13 ] = 1 - P [ Z ≤ 13]

And  P [ Z ≤ 13] will be find in z table for z (score) =

z ( score) = ( Z - μ₀ ) / σ

z (score) = (13 - 12 )/1

Then from z-table we find

P [ Z ≤ 13] = 0,8413

Finally

P [ Z > 13 ] = 1 - P [ Z ≤ 13]

P [ Z > 13 ] = 1 - 0,8413

P [ Z > 13 ] = 0,1587       or       P [ Z > 13 ] = 15,87 %

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this