I used to manually randomize the order of the problems but it was a lot of hassle and sometimes I could not achieve the level of "randomness" that I required. I discovered a cool website that made my life a lot easier.
Random.org is a site where you can arrange a list of items in random order. Just copy your list of questions, words or whatever and paste onto the form on the webpage. Next, click on the [Randomize] and let the website do its magic.
If you are not happy with the order ot the items, just click on the [Again] button.
Lastly, block copy the list and paste onto your document.
This is a screencap of the site. （And yes, I am aware there is an error one of the sentences.)