Y² + 8y + 15
since 8 and fifteen are positive, that means your factors are going to be positive
(y + )(y + )
What are the factors of 15 that add up to 8?
28°
a triangle = 180°
180°-140°= 40°
180°-68°= 112°
180°-112°-40°= 28°
10. 25% of 40 or 0.25 times 40 gives you 10.
also 25% = 1/4
so 1/4 x 40 = 10
The answer to your question is 29.875
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 :-)
