Problema Solution
Arthur can do a job in 30 min; Bonnie can do it in 40 min and Claire can do it in 60 min. How long will it take them if they work together?
Answer provided by our tutors
Arthur: 1 job/30 min
Bonnie: 1job/40 min
Clair: 1 job/60 min
Working together, rate is
1/30 + 1/40 + 1/60 = 4/120 + 3/120 + 2/120
= 9 jobs/120min
= 120min/9jobs
= 13⅓ min/1job