In an examination, the Average marks of 7 children was 20, that of 3 children was 45, that of another 4 children was 15 and that of 2 children was 0. What is the average marks of all the 16 children? (Correct to one decimal place)

20 20.9 4 4.9

20.9

Sum of marks of all the 16 students = 7 ×20 + 3×45 + 4×15 + 2×0 = 335 Average = \(\frac{335}{16}\) = 20.9