Saved Bookmarks
| 1. |
23. A motor boat whose speed is 35 km/hrin still water takes 3 hour more to go100 km upstream then to returndownstream to the same spot. Thespeed of the stream is |
|
Answer» Answer: 15 Step-by-step explanation: Let the speed of STREAM be x Time upstream = 100/35-x Time DOWNSTREAM = 100/35+x 100/35-x - 100/35+x = 3 100(35+x) - 100(35-x) = 3(35² - x²) 3500+100x - 3500 + 100x = 3675 - 3x² 3x² + 200X - 3675 = 0 DISCRIMINANT =200²+210²= 40000+44100=84100 x = -b±√84100/ 2A = -200±290/ 2*3 = 90/6 or -490/6 = 15 or -490/6 Speed of stream = 15 (speed cannot be negative) |
|