A bus passes two bridges of length 500 m and 325 m in 90 seconds and 60…
2020
A bus passes two bridges of length 500 m and 325 m in 90 seconds and 60 seconds respectively. The length (in m) of the bus is
- A.
25
- B.
27
- C.
22
- D.
30
Attempted by 2 students.
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Correct answer: A
Let the length of the bus be L metres and its speed be v m/s.
While crossing a bridge, the bus covers its own length plus the bridge length.
For the 500 m bridge: (L + 500)/v = 90.
For the 325 m bridge: (L + 325)/v = 60.
Divide the equations: (L + 500)/(L + 325) = 90/60 = 3/2.
2(L + 500) = 3(L + 325) gives 2L + 1000 = 3L + 975, so L = 25 m.