A study comparing birth weight to IQ found 255 subjects (sample 1) with extremely low birth weights had IQ scores at age 8 with a mean of 93.9 and a standard deviation of 15.6. The control group of 282 subjects (sample 2) with normal birth weights had IQ scores with a mean of 95.4 and a standard deviation of 13.2 at age 8. Construct a 95% confidence interval estimate of the difference between the mean IQs of the two groups. Do not assume the population standard deviations are equal. Does IQ score appear to be affected by weight? 1 Click the icon to view the table of critical values. Find the 95% confidence interval. < μ1 - μ2 < (Round to two decimal places as needed.) Does the confidence interval show that low birth weight affects IQ? A. No, because the confidence interval does not include zero. B. Yes, because the confidence interval includes zero. C. Yes, because the confidence interval does not include zero. D. No, because the confidence interval includes zero.
Image text
A study comparing birth weight to IQ found 255 subjects (sample 1) with extremely low birth weights had IQ scores at age 8 with a mean of 93.9 and a standard deviation of 15.6. The control group of 282 subjects (sample 2) with normal birth weights had IQ scores with a mean of 95.4 and a standard deviation of 13.2 at age 8. Construct a 95% confidence interval estimate of the difference between the mean IQs of the two groups. Do not assume the population standard deviations are equal. Does IQ score appear to be affected by weight? 1 Click the icon to view the table of critical values. Find the 95% confidence interval. < μ1 - μ2 < (Round to two decimal places as needed.) Does the confidence interval show that low birth weight affects IQ? A. No, because the confidence interval does not include zero. B. Yes, because the confidence interval includes zero. C. Yes, because the confidence interval does not include zero. D. No, because the confidence interval includes zero.
