The average age of three persons is 52 years. Their ages are in the proportion of 1:5:7. What is the age in years of the oldest one among them. Choose the correct choice:
A) 9 years B) 12 years C) 60 years D) 70 years E) 80 years
Explanation:   Let the age of three persons be x, 5x, 7x   = 13x/3 = 52   x= 12 years   Answer: Option 70 years
<result>D</result>
The average age of three persons is 52 years. Their ages are in the proportion of 1:5:7. What is the age in years of the oldest one among them.