Correct Option
To determine who completes the work first, the total time each individual takes to complete 100% of the work must be calculated.
Z can do 1/3 of the work in 13 days. Therefore, Z can complete the entire work in 13 × 3 = 39 days.
Comparing this with the time taken by W, X, and Y, Z completes the work in the shortest duration.
Incorrect Options
The time taken by other individuals to complete the entire work is calculated as follows:
- W can do 25% of the work in 30 days. Thus, W completes the entire work in 30 × 4 = 120 days.
- X can do 1/4 of the work in 10 days. Thus, X completes the entire work in 10 × 4 = 40 days.
- Y can do 40% of the work in 40 days. Thus, Y completes the entire work in 40 × (100/40) = 100 days.
Since W takes 120 days, X takes 40 days, and Y takes 100 days, all these durations are longer than the 39 days taken by Z. Therefore, W, X, and Y do not complete the work first.