Answer:
20
Steps-by-step explanation:
sorry mistake
Answer:
a) 
With:


b) 

c) 

d) 


Step-by-step explanation:
For this case we know the following propoertis for the random variable X

We select a sample size of n = 81
Part a
Since the sample size is large enough we can use the central limit distribution and the distribution for the sampel mean on this case would be:

With:


Part b
We want this probability:

We can use the z score formula given by:

And if we find the z score for 89 we got:


Part c

We can use the z score formula given by:

And if we find the z score for 75.65 we got:


Part d
We want this probability:

We find the z scores:



total cost = membership +cost per class* number of classes
y = 275+5*x
Choice C
Answer:
x=5 and 3
Step-by-step explanation:
x^2-8x+21=6
x^2-8x+21+16=6+16
(x-4)^2=1
(x-4)=±1, x=5 and 3
Answer:
Option (4)
Step-by-step explanation:
Vertices of the triangle are X(0, -4), Y(2, -3) and Z(2, -6).
Slope of XY (
) = 
= 
(
) = 
Similarly, slope of XZ (
) =
(
) = (-1)
Which should be (-1) if XY and XZ are perpendicular to each other.
Now we can say that XY and XZ are not perpendicular.
Therefore, Lydia's assertion that ΔXYZ is a right triangle is not correct.
Option (4) will be the answer.