What is the length of a train traveling at a constant speed of 90 meters per second, if it crosses Bridge A in 10 seconds, from the moment it enters the bridge to the moment its last carriage exits the bridge?
From the question itself, we can figure out that within these 10 seconds the train traveled the length of bridge A and the length of the train itself at 90 meter per second. So, the entire length of the bridge A and the train would be 10x90= 900 meter.
(1) The length of Bridge A is five times the length of the train.
Consider (1), Let's assume the length of train is x. So, the length of bridge A would be 5x. So, certainly, 5x+x=900. And, x would be 150.
So, A is sufficient to answer the question.
(2) During the journey, the train crosses Bridge B, which is four times the length of Bridge A, in 35 seconds.
Since, the length of bridge A is unknown, we are unable to reach a conclusion based on the information.
Answer A.