जॉइन Examsbookउत्तर : 3. "9"
A mother can do a certain job in x hours. Her daughter takes twice as long to do the job. Working together, they can do the job in 6 hours. How many hours does the mother take to do the job ?5
प्र: A mother can do a certain job in x hours. Her daughter takes twice as long to do the job. Working together, they can do the job in 6 hours. How many hours does the mother take to do the job ?
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उत्तर : 3. "9"
व्याख्या :
Answer: C) 9 Explanation: The mother completes the job in x hours.So, the daughter will take 2x hours to complete the same job. In an hour, the mother will complete 1/x of the total job.In an hour, the daughter will complete 1/2x of the total job. So, if the mother and daughter work together, in an hour they will complete 1/x + 1/2x of the job.i.e., in an hour they will complete 3/2x of the job. The question states that they complete the entire task in 6 hours if they work together.i.e., they complete 1/6 th of the task in an hour. Equating the two information, we get 3/2x = 1/6By solving for x, we get 2x = 18 or x = 9. The mother takes 9 hours to complete the job.