Final answer:
The repairman takes approximately 5.625 minutes to fix one pair of shoes by himself.
Step-by-step explanation:
Let x be the amount of time it takes for the repairman to fix one pair of shoes.
Since the assistant takes twice as long, their time can be represented as 2x.
Together, the repairman and assistant can fix 16 pairs of shoes in 8 hours, so their combined rate is 16 pairs / 8 hours = 2 pairs per hour.
Using the formula: Rate × Time = Work, we can set up the equation: (1/x + 1/(2x)) × 8 = 16.
Multiplying both sides by 2x to eliminate the fractions, we get: 2 + 1 = 32x.
Combining like terms, we have: 3 = 32x.
Dividing both sides by 32, we find: x = 3/32.
Therefore, it takes the repairman 3/32 of an hour, or approximately 5.625 minutes, to fix one pair of shoes by himself.