55/A is the answer
Hope this helps
Answer:

Step-by-step explanation:

Put the values of x from the table to the equation:

From the comment.
Convert the equation:
<em>multiply both sides by 4</em>

Put the values of y from the table to the equation:


Answer:

Step-by-step explanation:
The confidence interval for the population mean x can be calculated as:

Where x' is the sample mean, s is the population standard deviation, n is the sample size and
is the z-score that let a proportion of
on the right tail.
is calculated as: 100%-99%=1%
So, 
Finally, replacing the values of x' by 308, s by 17, n by 15 and
by 2.576, we get that the confidence interval is:

Answer:
Solution given:
The area of a circle =80.86cm²
we have:
The area of a circle =πr²
substituting value of area of circle we get
80.86cm=3.14*r²
dividing both side by 3.14
80.86/3.14=3.14*r²/3.14
25.75=r²
doing square root on both side

r=5.07cm
<u>The</u><u> </u><u>length</u><u> </u><u>of</u><u> </u><u>radius</u><u> </u><u>is</u><u> </u><u>5</u><u>.</u><u>0</u><u>7</u><u>cm</u>