Congratulations, you just made a confidence interval! But wait, how did we decide on the width of the interval? The middle of the interval is the sample mean. We start there, and then the "wiggle room" we give on either side of that center is called the margin of error (MOE). There's a formula for margin of error: 0 MOE = 2* √T This formula consists of three values: o is the standard deviation, n is the sample size, and z* is a multiplier that we choose based on the confidence level we need. Confidence levels are expressed as percentages, the most common are 90%, 95%, and 99%: * Confidence Z Level value 90% 1.645 95% 1.96 99% 2.576 Let's practice computing a margin of error. For our earlier example about houses, suppose the standard deviation was 14 years, and the sample size was 30. Use a confidence level of 95% and determine the margin of error: σ Remember, we'll use the formula MOE = 2* . First fill in the numbers for each part of the formula: √n σ= n = Now put it all together, rounding your answer to one decimal place: MOE = margin of error = years

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
Publisher:Carter
Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 22PFA
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Congratulations, you just made a confidence interval! But wait, how did we decide on the width of the interval?
The middle of the interval is the sample mean. We start there, and then the "wiggle room" we give on either
side of that center is called the margin of error (MOE). There's a formula for margin of error:
0
MOE = 2*
√T
This formula consists of three values: o is the standard deviation, n is the sample size, and z is a
multiplier that we choose based on the confidence level we need.
Confidence levels are expressed as percentages, the most common are 90%, 95%, and 99%:
*
Confidence Z
Level
value
90%
1.645
95%
1.96
99%
2.576
Let's practice computing a margin of error. For our earlier example about houses, suppose the standard
deviation was 14 years, and the sample size was 30. Use a confidence level of 95% and determine the margin
of error:
σ
Remember, we'll use the formula MOE = 2*
. First fill in the numbers for each part of the formula:
√n
=
σ=
n =
Now put it all together, rounding your answer to one decimal place:
MOE = margin of error =
years
Transcribed Image Text:Congratulations, you just made a confidence interval! But wait, how did we decide on the width of the interval? The middle of the interval is the sample mean. We start there, and then the "wiggle room" we give on either side of that center is called the margin of error (MOE). There's a formula for margin of error: 0 MOE = 2* √T This formula consists of three values: o is the standard deviation, n is the sample size, and z is a multiplier that we choose based on the confidence level we need. Confidence levels are expressed as percentages, the most common are 90%, 95%, and 99%: * Confidence Z Level value 90% 1.645 95% 1.96 99% 2.576 Let's practice computing a margin of error. For our earlier example about houses, suppose the standard deviation was 14 years, and the sample size was 30. Use a confidence level of 95% and determine the margin of error: σ Remember, we'll use the formula MOE = 2* . First fill in the numbers for each part of the formula: √n = σ= n = Now put it all together, rounding your answer to one decimal place: MOE = margin of error = years
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