Road accidents are one of the leading causes of disability in South Africa, in part because of the resulting traumatic brain injury. To examine the cognitive effects of traumatic brain injury, we...

Road accidents are one of the leading causes of disability in South Africa, in part because of the resulting traumatic brain injury. To examine the cognitive effects of traumatic brain injury, we measure the IQ of 200 adults with mild, moderate and severe brain injuries. We also measure the IQ of a group of healthy adults who did not sustain any injuries. Here are the average IQs for each group.

a) Construct a bar graph of the results.

b) What can you conclude from these results?