Autism may be marked by different patterns of brain growth during early life. Researchers measured brain volume (in milliliters, using an MRI) in 31boys who were later diagnosed with autism. Brain volume is also available for 11boys who did not develop autism; these 11boys serve as the control group. The sample statistics are presented for both groups in the table below. Assume that the population variances are equal. Use a sigificance level of 0.05 to test for a difference between the autism and control groups.

Groups Sample size Sample mean Sample SD

Autism (group 1) n₁= 31 y₁= 1274.65 s₁= 86.15

Control (group 2) n₂= 11 y₂= 1147.28 s₂= 68.93

A. State null hypothesis

B. State alternative hypothesis

C. The standard error of the estimated difference between the autism and control groups is what

D. What is the test statistics and p-value