Answer : There are total 13 questions out of which 10 is to be answered .The student can answer in the following ways:
⇒ 6 questions from part A and 4 from part B
⇒ 5 questions from part A and 5 from part B
⇒ 4 questions from part A and 6 from part B
⇒ total ways in the 1st case are 6C6 X7C4
⇒ total ways in the 2nd case are 6C5 X7C5
⇒ total ways in the 3rd case are 6C4 X7C6
= 6C6 X 7C4
6C5 X7C5 +6C4 X7C6
Applying nCr
= 266 ways.