1. 12-9×3×4+3=-93
2.3+4×3×9-12=99
3. 12-9+3×9×3×4=327
Well, if you just divide 4000 by 50, you can see that the answer will come out as:
<em><u>80
</u></em>~TO check: 80 multiplied by 50 would come out to the answer of 4,000.
<em>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</em><em><u>
</u>Hope this helped! :D</em>
Answer:

Step-by-step explanation:
For the equation
use the substitution
Then the equation will take look

Solve this quadratic equation:

Thus,

Answer:
The margin of error is of 0.3012, and it means that we should be 99% confident that the population mean would be within 0.3012 of the sample mean.
Step-by-step explanation:
Margin of error

In which
is the standard deviation and n is the size of the sample.
Standard deviation of 1.3
This means that 
She surveys 124 families
This means that 
Margin of error and meaning:



The margin of error is of 0.3012, and it means that we should be 99% confident that the population mean would be within 0.3012 of the sample mean.