It depends on what kind of distribution you want for the results. Do you want an even distribution like how rand(1,10) allows each outcome to be as common as every other outcome? Or do you want it to be like throwing 2 dice, where out of 36 outcomes 6 of them will be total 7, while only 1 of 36 times will the total be 12.
https://mircscripts.net/j6hi0Here's an example of using uneven distribution. Notice how you can get some unusual outcomes by having the v1 and v2 themselves be randoms. For your function wanting a random number to 1 decimal, an other way that's easier for you to read later on is to do something like:
set %protection-a $rand(0,109) / 10
I suspect you really intended your max to be 10.0 not 10.9
