Question

Jonathan can type 20 documents in 40 minutes ,and Susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document

Answer 1

Answer: 10 minutes

Step-by-step explanation:

1. Jonathan can type 20 documents in 40 minutes (20/40=1/2 per minute), Susan can type it in 30 minutes (20/30=2/3 per minute) and Jack can type it in 24 minutes (20/24=5/6 per minute), then you must add them to obtain the number of pages they wan write  in 1 minute working together:

$\frac{1}{2}+\frac{2}{3}+\frac{5}{6}=2pages$

2. Then, the time will it take them type the same document of 20 pages is:

$\frac{20}{2}=10minutes$