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carolinar7

  • one year ago

A field test for a new exam was given to randomly selected seniors. The exams were graded, and the sample mean and sample standard deviation were calculated. Based on the results, the exam creator claims that on the same exam, nine times out of ten, seniors will have an average score within 5% of 75%. Is the confidence interval at 90%, 95%, or 99%? What is the margin of error? Calculate the confidence interval and explain what it means in terms of the situation.

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  1. carolinar7
    • one year ago
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    @mathway

  2. jchick
    • one year ago
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    the exam creator claims that on the same exam, nine times out of ten, seniors will have an average score within 6% of 80%.

  3. jchick
    • one year ago
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    that means Confidence Interval is 90%

  4. jchick
    • one year ago
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    9 / 10 means 90 / 100 so, the Confidence Interval is 90% accurate

  5. jchick
    • one year ago
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    confidence interval = 80%±6%

  6. jchick
    • one year ago
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    so "Margin of Error" is 6%

  7. jchick
    • one year ago
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    in interval notation, confidence interval = (74%, 86%)

  8. jchick
    • one year ago
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    Do you understand what I have done here?

  9. jchick
    • one year ago
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    Does this make sense?

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