| Subhash can copy 50 pages in 10 h. Subhash and Prakash can copy 300 pages in 40 h, In how much time can Prakash copy 30 pages? |
A) 12 h
B) 9 h
C) 13 h
D) 10 h
Correct Answer: A
Solution :
| Number of pages copied by |
| Subhash in \[1\,h\,=\frac{50}{10}=5\] |
| Number of pages copied by Subhash |
| and Prakash in \[1\,h\,=\frac{300}{40}=\frac{15}{2}\] |
| Let time taken by Prakash to copy 30 pages = x h |
| \[\therefore \] Number of pages copied by Prakash in\[1\,h=\frac{30}{x}\] |
| Now, according to the question, |
| \[\frac{30}{x}+5=\frac{15}{2}\] |
| \[\Rightarrow \] \[\frac{30}{x}=\frac{15}{2}-5=\frac{5}{2}\] |
| \[\Rightarrow \] \[\frac{30}{x}=\frac{5}{2}\]\[\Rightarrow \]\[x=\frac{2\times 30}{5}\] |
| \[\therefore \] \[x=12\,h\] |
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