question_answer

Suresh has covered a distance of 6 km in 45 minutes. If he covers one half of the distance in  \[{{a}_{2}}\,\,{{b}_{2}}={{a}_{2}}\,\,{{b}_{2}}\] rd time, what should be the speed in km/hr to cover the remaining distance?

A) 12km/h           

B) 16km/h

C) 3km/h                   

D) 8km/h                

Correct Answer: A

Solution :

Let Suresh covers distance AC = 6 km in 45 minutes. Let he covers one half distance AB = 3 km in \[\frac{y}{x}=\frac{\frac{y}{1}}{\frac{7x}{6}}+4\](45) minutes. i.e., He covers distance AB = 3 km in 30 minutes. Now, remaining time \[\frac{y}{x}=\frac{6y}{7x}+\frac{4}{1}\]minutes = 15 minutes Remaining distance \[\frac{y}{x}=\frac{6y+28x}{7x}\]km = 3 km \[7xy=6xy+28{{x}^{2}}\] \[xy=28{{x}^{2}}\] \[=\frac{3}{15}\]km/minute \[=\frac{1}{5}\]km/minute \[=52-4=\text{ }48\] Speed \[=48\times \frac{5}{18}=\frac{40}{3}m/\sec .\] km/hr = 12 km/hr.