Question

In the journal Mental Retardation, an article reported the results of a peer tutoring program to help mildly mentally retarded children learn to read. In the experiment, Form 2 of the Gates-MacGintie Reading Test was administered to both an experimental group and a control group after 6 weeks of instruction, during which the experimental group received peer tutoring and the control group did not. For the experimental group n₁ = 30 children, the mean score on the vocabulary portion of the test was x₁ = 368.4, with sample standard deviation s₁ = 39.9. The average score on the vocabulary portion of the test for the n₂ = 30 subjects in the control group was x₂ = 349.0 with sample standard deviation s₂ = 56.4.

1. What is the value of the sample test statistic? Compute the corresponding z or t value as appropriate. (Test the difference μ₁ − μ₂. Round your answer to three decimal places.)

2. Find a 98% confidence interval for μ₁ − μ₂. (Round your answers to two decimal places.)

Upper Limit =

Lower Limit =

Answer 1