Problem Solving (PS) | The average (arithmetic mean) ages, in years, of the people in group A

The average (arithmetic mean) ages, in years, of the people in group A and group B are 41 and 36, respectively. The average age, in years, of the people in the two groups combined is 38. If there are no people in both group A and group B, what fraction of the people in the two groups combined are in group B?

A. 2/5
B. 1/2
C. 3/5
D. 2/3
E. 3/4

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