Answer:
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Step-by-step explanation:
Every confidence interval has associated z value. As confidence interval increases so do the z value associated with it.
The confidence interval can be calculated using following formula:

Where

is the mean value, z is the associated z value, s is the standard deviation and n is the number of samples.
We know that standard deviation is simply a square root of variance:

The confidence interval of 95% has associated z value of <span>1.960.
</span>Now we can calculate the confidence interval for our income:
Answer:
area of a square = side x side
Step-by-step explanation:
The area of a trapezpid is 1/2h×(b1+b2)
Answer:
Plan A last 0.75 hours or 45 minutes.
Plan B last 1.5 hours or 90 minutes.
Step-by-step explanation:
Let
be the number of hours that the plan A last, an
the number of hours of plan B. Then for the Wednesday you have:

And for the Thursday is:

Multiply the equation of Wednesday by -3:

Using the method of addition using this last equation and the equation of Thursday

Replacing the value of
in one of the equations
