question_answer

It can take 12 h to fill a swimming pool using two pipes. if the pipe of larger diameter is used for 4 h and the pipe of smaller diameter is used for 9 h, only half of the pool can be filled. How long would it take for each pipe to fill the pool separately? OR A man starts his job with a certain monthly salary and earns a fixed increment every year. If his salary was ` 1500 after 4 yr of service and ` 1800 after 10 yr of service. What was his starting salary and what is the annual increment?  

Answer:

Let diameter of larger pipe  and diameter of smaller pipe According to the question,                                  ...(i) (1)  and ?                (ii)(1) Multiplying Eq. (ii) by 3, then subtract from Eq. (i), we get                                                      (1)                           Putting the value of  in Eq. (i), we get                                                         (1)                            OR Let monthly salary ` and fixed increment ` According to the question,                               ...(i) (1) and                                  ...(ii) (1) On subtracting Eq. (ii) from Eq. (i), we get  (1+1)                                           On putting  in Eq(i), we get                                                                                                             (2) Hence, the monthly salary be ? 1300 and fixed increment be  ` 50.           (1)