train train......
Level
1
Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is....
The answer is 1.5.
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1 solution
let speed of the trains be Sa and Sb and length of the trains be La and Lb. So,Sa=La/27 (as it takes 27 seconds to cross man). similarly Sb=Lb/17. thus, La=27Sa and Lb=17Sb. ->So, La+Lb=27Sa+17Sb Now, Sa+Sb=(La+Lb)/23 (as it takes 23 seconds to cross each other when running in opposite directions) ->thus, La+Lb=23Sa+23Sb hence, 27Sa+17Sb=23Sa+23Sb Or Sa/Sb=3/2=1.5