7.B would have taken 10 hours
more than what A would have
taken to complete a task if each
of them worked alone. Working
together they can complete the
task in 12 hours. How many
hours would B take to do 50% of
the task?
(1) 30 (2) 15
(3) 20
(4) 10
Answers
Answer:
2) 15 hours
Step-by-step explanation:
we get x=20
so for B=X+10=30 hours
and 50% of 30 =15 hours
MARK AS BRAINIEST DUDE
B alone take 15 hrs to do 50% of the task
Step-by-step explanation:
Let say A would have completed the task in T Hrs
Then B alone would have Taken = T + 10 hrs
A's 1 hr work = 1/T
B's 1 hr work = 1/(T + 10)
A & B 's together 1 hr work = 1/T + 1/(T + 10) = 1/12
=> 12(T + 10 + T ) = T(T + 10)
=> 24T + 120 = T² + 10T
=> T² - 14T - 120 = 0
=> T² - 20T + 6T - 120 = 0
=> T(T - 20) + 6(T - 20) = 0
=> (T + 6)(T - 20) =0
=> T = 20 hrs
B alone would have Taken = 20 + 10 = 30 hrs to complete task
to complete 50 % Task = (50/100) * 30 = 15 hrs
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