The z score for a confidence level of 99% is 2.575.. You need to know this to complete this type of problem.. the other two commonly used confidence levels are 90% and 95% having z scores of 1.645 and 1.96 respectively. You need to memorize this!
To find the confidence interval, it will be defined as the sample mean plus/minus the margin of error.. Now to find the margin of error, divide the standard deviation of 12 by the square root of the number of elements in your sample(√250). Then take that result and multiply it by the Z score I mentioned above for a 99% confidence level.
In this case: the sample mean is 70 and the margin of error is approximately 1.95
So to calculate the confidence interval, do the following:
70 - 1.95 = 68.05 rounded to the nearest whole number is 68
70 + 1.95 = 71.95 rounded to the nearest whole number is 72
Looks like that would be the last choice. hope this helps.. it's been awhile since my work with statistics :-)
Answer:
A
Step-by-step explanation:
Since the pyramids are similar, the scale factor will be 3. So the height of the small pyramid is 6.3/3=2.1. The volume will be (1/3)*(2.1)*(2.3)^2=3.70
X is 8 y is 6 , sin (y/r) r=10. x^2+y^2 = r^2. cos(x/r) tan (y/x) the other 3 are probably cosecant secant and cotangent just do the inverse (flip them) r/x etc..
84+63i would be the complex conjugate of84-63i
