so I don't completely understand dummy activities(arrows) in AoA diagrams, so I decided to do some practice questions related to it. I was wondering if anyone have a look at my solution and tell me if i am right or what i did wrong, it would be great help! Thanks.
You don't seem to be following that approach. For example, your H is not 6 times as long as your A. Given that, here is the question - why do you need the dummy activity from Event 4 to Event 5? You can directly connect Activity D to Event 5. Similarly, you can directly connect Activity H to Event 6 and directly connect Activity I to Event 6.
However, if you do decide to make the length of the arrow represent the estimated duration of the activity, you may need some dummy activities to bridge the gaps. You can see other examples of dummy activities given in the American Society of Quality site here.