Correct Option (1)
To determine the time required to complete 40% of the work when X and Y work together, first calculate the individual time each person takes to complete the entire work.
- Person X completes 20% of the work in 8 days. Therefore, X completes 100% of the work in 8×20100=8×5=40 days.
- Person Y completes 25% of the work in 6 days. Therefore, Y completes 100% of the work in 6×25100=6×4=24 days.
Next, calculate the time taken for X and Y to complete 100% of the work together. Using the formula for combined work rate:
Combined time =TimeX+TimeYTimeX×TimeY=40+2440×24=64960=15 days.
Finally, calculate the time required to complete 40% of the work:
Time for 40% work =10040×15=0.4×15=6 days.
Incorrect Options:
Options 2, 3, and 4 are incorrect as the calculated time for completing 40% of the work when X and Y work together is 6 days, which corresponds to Option 1.