Step 1: Calculate the train's speed in meters per second (m/s).To convert from km/h to m/s, multiply by \( \frac{5}{18} \).Speed: \( 90 \times \frac{5}{18} = 5 \times 5 = 25 \, \text{m/s} \).
Step 2: Determine the total distance using the formula: Distance = Speed × Time.The total distance when a train crosses a platform is the sum of the train's length and the platform's length.Total Distance: \( 25 \, \text{m/s} \times 26 \, \text{s} = 650 \, \text{m} \).
Step 3: Find the length of the train.Total Distance = Length of Train + Length of Platform.\( 650 = \text{Length of Train} + 250 \).Length of Train: \( 650 - 250 = 400 \, \text{m} \).