For a standard normally distributed random variable <em>Z</em> (with mean 0 and standard deviation 1), we get a probability of 0.0625 for a <em>z</em>-score of <em>Z</em> ≈ 1.53, since
P(<em>Z</em> ≥ 1.53) ≈ 0.9375
You can transform any normally distributed variable <em>Y</em> to <em>Z</em> using the relation
<em>Z</em> = (<em>Y</em> - <em>µ</em>) / <em>σ</em>
where <em>µ</em> and <em>σ</em> are the mean and standard deviation of <em>Y</em>, respectively.
So if <em>s</em> is the standard deviation of <em>X</em>, then
(250 - 234) / <em>s</em> ≈ 1.53
Solve for <em>s</em> :
16/<em>s</em> ≈ 1.53
<em>s</em> ≈ 10.43
Y=-1/4x+7.5 is the right equation
Percent change = ((new value) - (old value))/(old value) × 100%
= (180 -135)/135 × 100%
= 33 1/3%
180 is about 33% greater than 135.
It's a linear function. The graph is a straight line, therefore we need only two points.
Select any value of x and calculate the value of y:
y = -3x + 4
for x = 0 → y = -3(0) + 4 = 4 → (0, 4)
for x = 2 → y = -3(2) + 4 = -2 → (2, -2)
The answer is A. Or 5 cm.
Hope this helps,
kwrob
