Attached with question and answer need solution for why 50/53.57 is taken and how we got this value.

Rishab Soni Best Answer

Hello. I'm glad you asked this question because I have previously answered a similar one. So let's get our basics clear first. So this is a Time and Distance questions where we work with Speed, Time and Distance (generally two of them are known and we calculate the third) Here The simple formula is Distance/(Speed of Train 1 + Speed of Train 2) Now let's see what data we have. We have only given the time taken by the trains, and not distance or speed. But we can calculate it. 1) Train 1 leaves A at 5 AM and Reaches B at 9 AM Thus, we get Train A takes 4 hours to complete the journey 2) Train 2 leaves B at 7 AM and reaches A at 10:30 AM Thus the time taken for the journey is 3.5 hours 3)Distance from A to B is fixed so we can assume a distance. Generally people take 100 but I recommend you to take the LCM of the speeds as Distance to ease your calculations. I am taking Distance as 140 (LCM of 4 and 3.5 X 10) Now we can calculate the speed of both the trains 4)Speed of Train 1 is 140/4 = 35 KMph Speed of Train 2 is 140/3.5 = 40 KMph Now we can apply the formula I had mentioned in top and get the answer but here is the tricky part. Train 1 and 2 don't start at the same time. Train A starts at 5 and 2 starts at 7. That means Train A already has run for 2 hours and have covered some distance by the time Train 2 starts. So let's calculate how much distance Train 1 would already have covered by the time Train 2 starts. Speed of A X Time already taken That is 35 KMph X 2 hours = 70 KMs so Train 1 has already covered 70 KMs by the time Train 2 started. So the remaining distance is 140-70 = 70 KMs Now we can put the formula Time already taken + ((Distance left / (Speed of 1 + Speed of 2) x 60) : multiplying 60 to covert decimal value into minutes 2 Hours + (( 70/ 35+40) x 60) 2 Hours + ((70/75)x60) 2 hours + (0.9333x60) 2 hours + 56 mins Add this to the earliest starting train time That is 5 AM + 2 Hours 56 mins you'll get answer as 7:56 AM Hope that helps you ☺️