Three batches of students have average ages 17, 19, and 23 years respectively. If their numbers are in the ratio 3 : 4 : 6, what is the overall average age of all the students?

উত্তর দেখান ও ব্যাখ্যা

উত্তর: (B) 20.38

ব্যাখ্যা

(3×17 + 4×19 + 6×23)/13 = 265/13 ≈ 20.38.