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Practice B

Significance of Experimental Results

Use the information below to answer the questions.

1. A school is testing whether a new curriculum is successful in raising final exam scores. The data show the scores of the classes that were taught with the new curriculum (the test group) and the classes that continued to use the old curriculum (the control group).

|Control |72 |87 |72 |78 |

|62 |52 |54 |29 |35 |

|39 |58 |30 |28 |34 |

|34 |36 |37 |64 |25 |

Significance of Experimental Results:

Practice B

1 a. The test scores will be the same for both groups.

b. There is a large difference between the two groups that is unlikely to be caused by chance. The school should reject the null hypothesis because the new curriculum is working to increase test scores at the school.

2 a. −2.5

b. Because the absolute value of z is 2.5, which is greater than 1.96, there is enough evidence to reject the null hypothesis with 95% certainty.

3. The bounce heights will be the same for each company’s product.

4. a. −1.5

b. Because the absolute value of z is 1.5, which is less than 1.96, there is not enough evidence to reject the null hypothesis with 95% certainty.

Sampling Distributions:

Practice B

1. convenience sample

2. simple random sample

3. stratified sample

4. systematic sample

5. Method B is the most accurate method because every student has an equal chance of being selected.

6. No; 52% ± 2% ’ 50% to 54% and 48% ± 2% ’ 46% to 50%. The intervals overlap, so the survey does not clearly indicate the majority’s preference.

7. Yes; 58% ± 5% ’ 53% to 63% and 42%

± 5% ’ 37% to 47%. The intervals do not overlap. The survey clearly shows the majority’s preference.

Fitting to a Normal Distribution:

Practice B

1. 0.16

2. 0.93

3. 0.16

4. 0.09

5. 0.19

6. No, 14 of the 20 people have ages below the mean.

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