Question

11. A, B and C can do a job in 12 h. 20 h and 30 h respectively. If they all work together, how
long will they take to complete the job?​

Answer 1

Answer:

20 hours 36 minutes

Step-by-step explanation:

Mean = 12+20+30

--------------

3

= 62

-----

3

= 20.6

1 hour = 60 minutes

60÷10=6minutes

Let the number multiplied be x

Therefore, 6x= 6 × 6 = 36 minutes

20.6x = 1 × 20 + 36 = 20 hours 36 minutes

Answer 2

Answer:

6 hours

A=1/12

B=1/20

C=1/30

they work together

so,

A+B+C

1/12+1/20+1/30

LCM is 60

5/60+3/60+2/60

10/60

1/6

6 hours

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