Read the passage below and solve the questions based on it.
Every morning Ravi and Beena start walking from A and B respectively towards each other. They meet at C. Ravi always starts at 5:30 am and Beena starts at 4:45 am. Ravi’s speed is 6 km/h, whereas Beena’s speed is 5 km/h.
One fine morning, Beena started late by a few minutes and hence, met Ravi who started on time at D in between CB. CD = 2.5 km. By how many minutes was Beena late in starting on that day?