Two cyclists start from the same place in opposite directions. One goes towards north at 18 kmph and the other goes towards south at 20 kmph. What time will they take to be 47.5 km apart?
Speed of cyclist 1 S1 = 18 kmph
Speed of cyclist 2 S2 = 20 kmph
To find: Time taken by both of them to be 47.5 km apart
Now, at 1 hour, the distance between them = (18 + 20) km = 38 km
So, time to be 47.5 km apart = (1/38) x 47.5 = 5/4 hours (by using unitary method)
Or according to option, 1 ¼ hours (converting into mixed fraction)
They will take 1 ¼ hours to be 47.5 km apart.