Grade 11 · Math · Algebra 2

11th grade Confidence intervals from a sample, for averages and for percents worksheet

6 printable versionsBuilding Confidence10 questions · answer keyFree · no account

Level: Building Confidence · On Level · Challenge Me

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Confidence intervals from a sample, for averages and for percents

Grade 11 Math Worksheet - Building Confidence

NameDate

Circle the best answer, or write your answer on the line.

Bo weighs 25 random apples from a market; the sample SD is 15 grams. What is the standard error of the mean?
Esme asks 64 random students their reading minutes; the sample SD is 8 minutes (one says 'all weekend'). What is the standard error of the mean?
Read this first
Multiplier table for confidence intervals (standard normal values)
confidence level multiplier z*
90% 1.645
95% 1.96
99% 2.576
3.
Using the table, which multiplier does Jun use for a 95% interval?
- 2.576
- 1.645
- 1.96
4.
Using the table, which level gives Kira the widest interval?
- 95%
- 99%
- 90%
5.
Using the table, what multiplier goes with 90% for Luz?
- 1.96
- 1.645
- 0.90
6.
Milo's interval is 42 ± 3 minutes. What is the 42?
- The margin of error
- The sample size
- The sample mean
7.
Noah's interval is 42 ± 3 minutes. What are its two ends?
- 39 and 42 minutes
- 39 and 45 minutes
- 42 and 45 minutes
8.
How does Pia get the margin of error?
- Mean × sample size
- Multiplier × standard error
- SD ÷ mean
9.
Ren's 95% interval for mean sleep is 7.6 to 8.2 hours. What does it estimate?
- Each student's own sleep
- The sample's largest value
- The true mean for everyone
10.
Why must Tala's sample be random for an interval to make sense?
- So it fairly stands for the group
- So the mean is 0
- So the numbers come out whole and neat

Confidence intervals from a sample, for averages and for percents. Every version has 10 questions, and the answer key prints on the second page.

I can find the standard error of a mean, s ÷ √n, and of a proportion, √(p(1 − p) ÷ n).
I can read the multiplier from a table (1.645, 1.96, 2.576) and build an interval from sample data.
I can say how sample size and confidence level change the width.
I can say what an interval does and doesn't claim, and use it to judge a claim.

Standard: S-IC.B.4

confidence interval: A range of believable values for the true mean or percent

standard error: How much a sample result tends to vary

margin of error: Multiplier × standard error, added and subtracted

multiplier z*: A table number for the confidence level

sample proportion p: The share of the sample with the trait

Your child divided by n. The standard error of a mean divides the SD by the square root of n.

Your child found the standard error but didn't multiply by the table's 1.96. The margin of error is multiplier × standard error.

Your child used the rough margin 1 ÷ √n. With the sample's own percent, the margin is 1.96 × √(p(1 − p) ÷ n).

What is the most common mistake with confidence intervals from a sample, for averages and for percents?

Your child divided by n. The standard error of a mean divides the SD by the square root of n.

Are these 11th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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