Answer:
3x + 2y = 12
Step-by-step explanation:
The standard form is expressed as Ax + By = C
Answer:
The amount invested at 4% is $20,500 and the amount invested at 10% is $500
Step-by-step explanation:
Let
x -----> the amount invested at 4%
(21,000 -x) ----> the amount invested at 10%
we know that
The interest of the amount invested at 4% plus the interest of the amount invested at 10% must be equal to $870


so

Solve for x





therefore
The amount invested at 4% is $20,500 and the amount invested at 10% is $500
-2w^2=66.54-201.02
-2w^2= -134.48
w^2 = 134.48/2
w=square root of (67.24)=8.20
Answer:
yes
Step-by-step explanation:
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:


