Answer the Question. -A Researcher Looks at the Percentage of People Having High

Answer the question.
-A researcher looks at the percentage of people having high blood pressure amongst those who exercise regularly and amongst those who do not exercise regularly.
She selects 300 people under 40, of whom 100 exercise regularly and 200 do not. Among those who
Exercise regularly the rate of high blood pressure is 10% and among those who do not exercise
Regularly it is 15%.
She then selects 300 people over 40, of whom 200 exercise regularly and 100 do not. Among those
Who exercise regularly the rate of high blood pressure is 30% and among those who do not exercise
Regularly it is 35%.
However when she combines both age groups she finds that among those who exercise regularly
The rate of high blood pressure is 23.3% and among those who do not exercise regularly it is 21.7%.
Explain how the apparent inconsistency in these results came about.

A) Mistakes must have been made in measuring blood pressures.
B) Those that do not exercise regularly must be receiving some other treatment to lower their blood pressure.
C) The people in the "regular exercise" group probably started exercising because they have high blood pressure.
D) The group that exercises regularly contains a greater proportion of older people than the group that does not exercise regularly. So when the age groups are combined, the "regular
Exercise" group has a higher rate of high blood pressure.