Answer:whats the question
Step-by-step explanation:question?
Diameter of the circle in the middle = 8 ft
Radius of the circle in the middle :



Thus, the radius of the circle in the middle = 4 ft
Area of the entire circle :





Thus, the area of the entire circle = 314 ft
Area of the circle in the middle :




Thus, the area of the circle in the middle = 50.24 ft
Area of the shaded portion :
= Total area of the figure - Area of the circle in middle


▪︎Therefore, the area of the shaded portion = <u>263.76 ft</u>
Answer:
a) The mean is 
b) The standard deviation is 
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
The probability a student selected at random takes at least 55.50 minutes to complete the examination equals 0.6915.
This means that when X = 55.5, Z has a pvalue of 1 - 0.6915 = 0.3085. This means that when 
So




The probability a student selected at random takes no more than 71.52 minutes to complete the examination equals 0.8997.
This means that when X = 71.52, Z has a pvalue of 0.8997. This means that when 
So




Since we also have that 





Question
The mean is 
The standard deviation is 
Answer:


Step-by-step explanation:
We have two random variables X and Y.
and given that X=x, Y has uniform distribution (0,x)
From the definition of the uniform distribution we have the densities for each random variable given by:


And on this case we can find the joint density with the following formula:

And multiplying the densities we got this:

Now with the joint density we can find the expected value E(Y|x) with the following formula:

And replacing we got:
