An office has two envelope stuffing machines. Machine A can stuff a batch of envelopes in 5 hours, while Machine B can stuff a batch of envelopes in 3 hours. How long would it take the two machines working together to stuff a batch of envelopes?

Question

An office has two envelope stuffing machines.  Machine A can stuff a batch of envelopes in 5 hours, while Machine B can stuff a batch of envelopes in 3 hours.  How long would it take the two machines working together to stuff a batch of envelopes?

anonymous · Answer

hello @pooja195

anonymous · Answer

hmm... let's see what I can do:
given:
machine A: 1 batch/ 5 hours 
machine B: 1batch/ 3 hours 

together to make 1  batch:
1 batch= (rate of A)(time spent) + (rate of b)(time spent)
1= 1/5t + 1/3t

evaluate and solve for t (time spent together)

pooja195 · Answer

i would do the reciprocal right?

anonymous · Answer

i'm not sure if it is necessary though

first simplify the two terms on the right side, then let's see what's next

pooja195 · Answer

im think 3t+5t=15
                  8t=15
                     t=15/8?

anonymous · Answer

oh wow, lol i guess your right ^_^ got the same

oh yeahhh, now I get it... reciprocal of 1 is 1, so yes we can do that

pooja195 · Answer

LOL xD ok So, it looks like it will take the two machines, working together, 1.875 hours to stuff a batch of envelopes.

anonymous · Answer

eggsactly :D

pooja195 · Answer

yay!!! thanks :)

anonymous · Answer

np! :P