Answer:
a)
b) 
c) 
d) 
Step-by-step explanation:
Let X the random variable that represent the number of material anomalies occurring in a particular region of an aircraft gas-turbine disk. We know that
The probability mass function for the random variable is given by:
And f(x)=0 for other case.
For this distribution the expected value is the same parameter
,
, 
a. Compute both P(X≤4) and P(X<4).
Using the pmf we can find the individual probabilities like this:




b. Compute P(4≤X≤ 8).







c. Compute P(8≤ X).


d. What is the probability that the number of anomalies exceeds its mean value by no more than one standard deviation?
The mean is 4 and the deviation is 2, so we want this probability





Answer:
24+24x I believe is the answer. Good luck on your test :)
Get the derivative:
<em>y</em> = (9 - <em>x</em>²)¹ʹ³
d<em>y</em>/d<em>x</em> = 1/3 (9 - <em>x</em>²)⁻²ʹ³ d/d<em>x</em> [9 - <em>x</em>²]
d<em>y</em>/d<em>x</em> = 1/3 (9 - <em>x</em>²)⁻²ʹ³ (-2<em>x</em>)
d<em>y</em>/d<em>x</em> = -2/3 <em>x</em> (9 - <em>x</em>²)⁻²ʹ³
Evaluate it at <em>x</em> = 1 :
d<em>y</em>/d<em>x</em> (1) = -2/3 • 8⁻²ʹ³
Since 8 = 2³, we have
8⁻²ʹ³ = 1 / 8²ʹ³ = 1 / (2³)²ʹ³ = 1 / 2² = 1/4
Then the tangent line has equation
<em>y</em> - 2 = 1/4 (<em>x</em> - 1) → <em>y</em> = 1/4 <em>x</em> + 7/4