Answer:
A
Step-by-step explanation:
if (x1,y1) and (x2,y2) are the extremities of diameter,then eq. of circle is
(x-x1)(x-x2)+(y-y1)(y-y2)=0
reqd. eq. is (x+1)(x-5)+(y+9)(y-1)=0
center is (2,-4)
r=√(2²+(-4)²-(-14))
=√(4+16+14)
=√(34)
eq. of circle is (x-2)²+(y+4)²=34
or
(x²-4x)+(y²+8y)=14
(x²-4x+4)+(y²+8y+16)=14+4+16
(x-2)²+(y+4)²=34
Answer:
21
Step-by-step explanation:
Using<em> Simple Random Sampling</em>, we can estimate the sample size by the formula
where
n = sample size
Z = the z-score corresponding to the confidence level 99.5%
S = the assumed standard deviation = 3 seconds
e = margin of error = 2 seconds
<em>It is worth noticing that the higher the confidence level, the larger the sample should be. </em>
The z-score corresponding to a confidence level of 99.5% can be obtained either with a table or the computer and equals
Z = 3.023
Replacing the values in our formula
So the size of the sample should be at least 21.