Estimate a population from a sample survey, with the margin of error given

Answer Key - Grade 9 Math Worksheet - Building Confidence

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

1. 1.

   Esme surveyed a random sample of 100 students: a mean of 8.4 hours of sleep a night, margin of error 0.3 hours. What is the upper end of the interval for all students?

   8.7
2. 2.

   Jun surveyed a random sample of 150 students: a mean of 24 minutes of reading a day, margin of error 3 minutes. What is the lower end of the interval for all students?

   21
3. 3.

   Kira surveyed a random sample of 120 students: a mean of 3.2 library books borrowed last month, margin of error 0.5 books. What is the upper end of the interval for all students?

   3.7
4. 4.

   Luz surveyed a random sample of 80 students: a mean walk to school of 14.5 minutes, margin of error 1.5 minutes. What is the lower end of the interval for all students?

   13
5. 5.

   Milo surveyed a random sample of 200 students: 46% walk to school, margin of error 7 percentage points. What is the upper end of the interval for all students?

   53
6. 6.

   Noah surveyed a random sample of 400 students: 62% bring lunch from home, margin of error 5 percentage points. What is the lower end of the interval for all students?

   57
7. 7.

   Ren surveyed a random sample of 625 students: 54% like the new playground, margin of error 4 percentage points. What is the lower end of the interval for all students?

   50
8. 8.

   In a random sample of 120 students, Tala found a mean of 6.5 hours of outdoor play a week, with a margin of error of 0.6 hours. Which statement fits all students at the school?

   • The school's mean is likely between 6.2 and 6.8 hours.
   • The school's mean is likely between 6.5 and 7.1 hours.
   • The school's mean is exactly 6.5 hours.
   • The school's mean is likely between 5.9 and 7.1 hours.
9. 9.

   In a random sample of 90 students, Ari found a mean bus ride of 18 minutes, with a margin of error of 2 minutes. Which statement fits all students at the school?

   • The school's mean is likely between 17 and 19 minutes.
   • The school's mean is likely between 18 and 20 minutes.
   • The school's mean is likely between 16 and 20 minutes.
   • The school's mean is exactly 18 minutes.
10. 10.

    In a random sample of 400 students, Bo found that 41% play an instrument, with a margin of error of 5 percentage points. Which statement fits all students at the school?

    • The school's percent is likely between 38.5% and 43.5%.
    • The school's percent is likely between 36% and 46%.
    • The school's percent is exactly 41%.
    • The school's percent is likely between 41% and 46%.