Explanation Total runs scored in 10 matches = 10 × 38.9
Total runs scored in first 6 matches = 6 × 42
Total runs scored in the last 4 matches = 10 × 38.9 - 6 × 42.
Average of the runs scored in the last 4 matches = ( 10×38.9−6×4 )/24.
=(389−252)/4.
=137/4.
=34.25.