To convert cups to deciliters using the provided conversion data, we first need to convert cups to liters and then convert liters to deciliters.
According to the conversion table, 1 cup is equal to 0.237 liters.
Now, for 9 cups: \[ 9 \text{ cups} \times 0.237 \text{ liters/cup} = 2.133 \text{ liters} \]
Next, since 1 liter is equal to 10 deciliters, we convert liters to deciliters: \[ 2.133 \text{ liters} \times 10 \text{ dL/liter} = 21.33 \text{ dL} \]
Rounding 21.33 to the nearest tenth gives us: \[ 21.3 \text{ dL} \]
So, the answer is 21.3 dL.