Correct Answer: Option B -
3/10
Explanation:Let Sam's rate be R. Mohit's is 2R, Ayna's is 2R/3. The work done in 3 days is (R+2R) + (R+2R/3) + (2R+2R/3) = 9R. Sam's work in this period is R+R = 2R. The fraction of work done by Sam is 2R/9R = 2/9. Whoops, rechecking... Let Sam's work rate be 3 units/day. Mohit's rate is 6 units/day. Ayna's rate is 2 units/day. Total work is 20*3=60 units. Day 1: S+M=9. Day 2: S+A=5. Day 3: M+A=8. Cycle of 3 days does 22 units. 2 cycles = 44 units in 6 days. Remaining 16 units. Day 7: S+M=9. Rem: 7. Day 8: S+A=5. Rem: 2. Day 9: M+A does 2 units in 2/8=1/4 day. Sam works on Day 1,2,4,5,7,8. Sam's total work: 3+3+3+3+3+3=18. Fraction = 18/60 = 3/10.