Answer:
3 hours 56 minutes
Step-by-step explanation:
An experienced surveyor can survey a roadbed in = 7 hours
work done by experienced surveyor in one hour = [tex]\frac{1}{7}[/tex]
An apprentice surveyor needs time to survey the same = 9 hours
work done by apprentice surveyor in one hour = [tex]\frac{1}{9}[/tex]
If the two work together, time taken to complete the job = [tex]\frac{1}{7}[/tex] + [tex]\frac{1}{9}[/tex]
= [tex]\frac{16}{63}[/tex]
= [tex]\frac{1}{3.9375}[/tex]
time taken together to complete the job 3.9375 hours or 3 hours 56 minutes.
