First off, it's not a dumb or stupid question. It's not easy to learn & I still have to refer to the chart after using it for 30+ years. It IS an easy way to measure humidity & it's pretty accurate. & it's the only thing I use.
The chart I have has 100, 102, & 104 degree dry bulb conversion, but because we are mainly interested in the 100 degree one, that is what I will post.
DB=DRY BULB, WB=WET BULB, RH=RELATIVE HUMIDITY.
100DB-82WB = 46% RH
100DB-83WB = 49%RH
100DB-84WB = 51%RH
100DB-85WB = 54%RH
100DB-86WB = 56%RH
100DB-87WB = 59%RH
100DB-88WB = 62%RH
100DB-89WB = 65%RH
If you have the chart, you should be able to figure out the rest, If you can't let me know. It appears you are reading the chart correctly.
I don't know what GQF suggest you use for temperature & humidity, but this is what I have
Chicken eggs -99.5 (I use 100) during the first 18 days. 99 the last three days (I use 100)
Humidity- 85-87WB (I use 85 =54% RH) during the first 18 days. 90-94 the last 3 days (I use 90 =68%RH)
Now There are a lot of opinions on what humidity to run, I'm simply telling what I run. My hatches, with my incubators, with my own eggs, using these figures give me 98 %+ hatch rates.
The best way to see if the humidity you are using is correct for you would be candle the eggs & mark the progress of the air cell