Average score after 50 innings = $46.4$ Total score after 50 innings = $50 \times 46.4 = 2320$ Average score after 60 innings = $46.4 + 2.6 = 49$ Total score after 60 innings = $60 \times 49 = 2940$ Runs scored in the last 10 innings = $2940 - 2320 = 620$ Average score in these 10 innings = $62$

Alternatively, Initial average after 50 innings = $46.4$ After 10 more innings, his average increases by 2.6 to become 49. Runs required to achieve this increase: Runs to fill the gap in average for the last 50 innings = $2.6 \times 50 = 130$ Runs needed to maintain an average of 49 in the next 10 innings = $49 \times 10 = 490$ Total runs scored in the last 10 innings = $130 + 490 = 620$ Average score in these 10 innings = $62$ Hence, the average score in the last 10 innings is 62.