Answer:
3.75 hours
Explanation:
The receptionist takes n hours to do 1 day's worth of work.
The assistant takes 4n hours to the 1 day's worth of work.
In 1 hour, the receptionist does 1/n amount of work.
In 1 hour, the assistant does 1/(4n) amount of work.
Working together, in 1 hour, they do this amount of work:
1/n + 1/(4n)
Working together, the 2 workers do the job in 3 hours.
Working together, in 1 hour, they do this amount of work:
1/3
1/n + 1/(4n) = 1/3
Multiply both sides of the equation by the LCD, 12n.
12 + 3 = 4n
4n = 15
n = 15/4
n = 3.75
Answer: 3.75 hours