Question

21. Mr. Rahul can do a job in 45 minutes, while his son can do in 2 hours. How long will
it take them working together?
A) 18m B) 33m C) 350 D) 1h 21m E) 1 hr. 3im​

Answer 1

Answer:

33 minutes

Step-by-step explanation:

45 minutes = 45 minutes

2 hours = 2 × 60 = 120 minutes

Time taken working together =

xy/x + y

= 45 × 120/45 + 120

= 45 × 120/165

= 32.7 min

= 33 minutes

Answer 2

Step-by-step explanation:

1/x + 1/y = 1/xy

1/45 + 1/120 = 1/xy

45+120/45×120 = 1/xy

165/5400 = 1/xy

5400/165 = xy

32.75

= 33 minutes