Answer:

Step-by-step explanation:
Given

-- City C
--- City K
Required
Determine the 90% confidence interval
This is calculated using:

Calculating 




For a 90% confidence level, the z-score is 1.65. So:

Calculating the standard deviation 

So:


So:


Answer: 3100
Step-by-step explanation:
to find the area of something u must multiply both sides
Answer:
Marco's age is 7 years old
Step-by-step explanation:
Let
x ----> Marco's age
y ----> Paolo's age
we know that
---->
----> equation A
----> equation B
substitute equation A in equation B


Solve the quadratic equation
The formula to solve a quadratic equation of the form
is equal to

in this problem we have

so

substitute in the formula





Remember that the solution cannot be a negative number
so
The solution is x=7
therefore
Marco's age is 7 years old
The product of 12 and -5 is -5(12) = -60. Note that 12(-5) = -60 also.