Answer:
a)
We want this probability:
And using the z score formula given by:
We got:
b) For this part we want to find a value a, such that we satisfy this condition:
(a)
(b)
Both conditions are equivalent on this case. We can use the z score again in order to find the value a.
As we can see on the figure attached the z value that satisfy the condition with 0.75 of the area on the left and 0.25 of the area on the right it's z=0.674. On this case P(Z<0.674)=0.75 and P(z>0.674)=0.25
If we use condition (b) from previous we have this:
But we know which value of z satisfy the previous equation so then we can do this:
And if we solve for a we got
So the value of height that separates the bottom 75% of data from the top 25% is 45.707.
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Part a
Let X the random variable that represent the heights of a population, and for this case we know the distribution for X is given by:
Where and
And we want this probability:
And using the z score formula given by:
We got:
We want this probability:
And using the z score formula given by:
We got:
Part b
For this part we want to find a value a, such that we satisfy this condition:
(a)
(b)
Both conditions are equivalent on this case. We can use the z score again in order to find the value a.
As we can see on the figure attached the z value that satisfy the condition with 0.75 of the area on the left and 0.25 of the area on the right it's z=0.674. On this case P(Z<0.674)=0.75 and P(z>0.674)=0.25
If we use condition (b) from previous we have this:
But we know which value of z satisfy the previous equation so then we can do this:
And if we solve for a we got
So the value of height that separates the bottom 75% of data from the top 25% is 45.707.
Answer:
The zeros of the function are;
x = 0 and x = 1
Step-by-step explanation:
The zeroes of the function simply imply that we find the values of x for which the corresponding value of y is 0.
We let y be 0 in the given equation;
y = x^3 - 2x^2 + x
x^3 - 2x^2 + x = 0
We factor out x since x appears in each term on the Left Hand Side;
x ( x^2 - 2x + 1) = 0
This implies that either;
x = 0 or
x^2 - 2x + 1 = 0
We can factorize the equation on the Left Hand Side by determining two numbers whose product is 1 and whose sum is -2. The two numbers by trial and error are found to be -1 and -1. We then replace the middle term by these two numbers;
x^2 -x -x +1 = 0
x(x-1) -1(x-1) = 0
(x-1)(x-1) = 0
x-1 = 0
x = 1
Therefore, the zeros of the function are;
x = 0 and x = 1
The graph of the function is as shown in the attachment below;
