Answer:
hope its correct and does helps u
You subtract 13 from both sides, leaving us with:
x = 74 - 13
x = 61. this answer has not been listed, but it is correct.
maybe you made a typo when writing the actual problem down? if not, 61 is the answer.
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 :-)
Convert 20 min to hrs: 20/60 = 1/3 hr
Let t = time on the bikethent-(1/3) = time on the bus
Write a dist equation Dist = speed * time:Bike dist + bus dist = 26 mi6t + 30[t-(1/3)] = 26:6t + 30t - 10 = 2636t = 26 + 1036t = 36t = 1 hr on the bike
6 mph for 1 h = 6 mi from house to the bus station
Check solution by finding the distance6(1) + 30(2/3) =6 + 20 = 26 mi
