Speed of a boat in still water is 14 km/h while the speed of stream is ____ km/h. Total time taken by the boat to go 140 km upstream and 210 km downstream is ____ hours. The values given in which of the following options will fill the blanks in the same order in which it is given to make the above statement true:
I. 6, 26
II. 4, 22.5
III. 5, 25
IV. 7, 24

For I: Speed of boat = 14 km/h Speed of stream = 6 km/h Speed in upstream = 14 – 6 = 8 km/h Speed in downstream = 14 + 6 = 20 km/h Total time = 140/8 + 210/20 = 17.5 + 10.5 = 28 hours So, I can’t be the answer. For II: Speed of boat = 14 km/h Speed of stream = 4 km/h Speed in upstream = 14 – 4 = 10 km/h Speed in downstream = 14 + 4 = 18 km/h Total time = 140/10 + 210/18 = 14 + 11.67 = 25.67 hours So, II can’t be the answer. For III: Speed of boat = 14 km/h Speed of stream = 5 km/h Speed in upstream = 14 – 5 = 9 km/h Speed in downstream = 14 + 5 = 19 km/h Total time = 140/9 + 210/19 = 15.56 + 11.05 = 26.61 hours So, III can’t be the answer. For IV: Speed of boat = 14 km/h Speed of stream = 7 km/h Speed in upstream = 14 – 7 = 7 km/h Speed in downstream = 14 + 7 = 21 km/h Total time = 140/7 + 210/21 = 20 + 10 = 30 hours So, IV can’t be the answer.