A) \[17\,\,\operatorname{seconds}\]
B) \[\frac{500}{29}\operatorname{seconds}\]
C) \[\frac{1200}{29}\operatorname{seconds}\]
D) \[\frac{700}{29}\operatorname{seconds}\]
Correct Answer: B
Solution :
Let A take \[x\] second in covering \[1000\,\,m\] and \[b\] takes \[y\] seconds According to the question, \[x+20=\frac{900}{1000}y\] \[\Rightarrow \] \[x+20=\frac{9y}{10}\] ? (i) and, \[\frac{950}{1000}x+25=y\] ? (ii) From equation (i), \[\frac{10x}{9}+\frac{200}{9}=y\] \[\Rightarrow \] \[\frac{10x}{9}+\frac{200}{9}=\frac{950x}{1000}+25\] \[\Rightarrow \] \[\frac{10x}{9}+\frac{200}{9}=\frac{19x}{20}+25\] \[\Rightarrow \] \[\frac{10x}{9}-\frac{19x}{20}=25-\frac{200}{9}\] \[\Rightarrow \] \[\frac{200x-171x}{180}=\frac{225-200}{9}\] \[\Rightarrow \] \[\frac{29x}{180}=\frac{25}{9}\] \[\Rightarrow \] \[x=\frac{25}{9}\times \frac{180}{29}=\frac{500}{29}\]secondsYou need to login to perform this action.
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