Another math problem please..?

Question

Group A of workers can do a job in 8 days. after group A has worked for 3 days, another group B joins A and together they complete the job in 3 more days. in how many days could group B have done the job alone?

thank you for answering..really appreciate it.. :)

Answer 1

so if A work for 3 days then they complete 3/8 job before B joins

so they have 5/8 job left

in that 3 days A can complete another 3/8 so it leaves 2/8 for B in 3 days

so set up proportion

0.25/3= 1/x

x= 12

so it would take B 12 days to do job alone  

Answer 2

a does 1/8 work in 1 day in 3 days 3/8 work is finished

in next 3 days a would do another 3/8 work

so b does balance 2/8 work in 3 days

so b does (2/8)/3 work =2/24 work in one day

b requires 24/2 i.e. 12 days to do the job

Answer 3

Speed of Group A:

= 1/8

Work remaining after 3 days:

= 1 - 3(1/8)

= 8/8 - 3/8

= 5/8

Speed of Group B (x):

3(1/8 + x) = 5/8

3/8 + 3x = 5/8

3x = 5/8 - 3/8

3x = 2/8

x = 2/24 or 1/12

Group B could finish the job in:

= 1/(1/12)

= 12

Answer: 12 days it will take for Group B to finish the job alone.

Answer 4

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