Time = Distance over speed help?

So were doing an assignment which involves using distance over speed. I have the answers, except my teacher has marked them wrong and I don't understand why. I put: 16.2/8 = 2.025 0.025*60 = 1.5 = 2 hours 2 mins (rounded up from 1.5) She circled the answer and said it should be 2hrs 15 minutes. Why? She's also said the following are wrong: 14.6/8 = 1.825 0.825*60 = 49.5 = 1 hour 50 mins And 0.9/8 = 0.1125 0.1125*60= 6.75 = 1 hour 7mins She's said they're all wrong. I don't understand why. Please help?