1 1 vote John jogs on track $\text{A}$ at $6$ kmph and Mary jogs on track $\text{B}$ at $7.5$ kmph. The total length of tracks $\text{A}$ and $\text{B}$ is $325$ metres. While John makes $9$ rounds of track $\text{A}$, Mary makes $5$ rounds of track $\text{B}$. In how many seconds will Mary make one round of track $\text{A}$ ________ Quantitative Aptitude cat2019-2 quantitative-aptitude speed-distance-time numerical-answer + – go_editor 14.2k points 1.8k views answer comment Share Follow Print 0 reply Please log in or register to add a comment.
1 1 vote Ans is (48) Let the lengths of tracks A and B be $x,y$ respectively. Speed of John and Mary in m/s : $\frac{5}{3},\frac{25}{12}\;\left(\text{by multiplying speed in km/h by}\; \frac{5}{18} \right)$ Given $x+y=325$ and $\frac{9x}{\frac{5}{3}}=\frac{5y}{\frac{25}{12}}$ Solving these two equations , we get $x=100\;\text{mtr}$ $\therefore$ Time taken by Mary to complete track A : $\frac{100\;\text{mtr}}{\frac{25}{12}\text{m/s}}=48$ seconds. haralk10 answered Apr 15, 2021 haralk10 838 points comment Share Follow 0 reply Please log in or register to add a comment.