To determine the percentage of farmers with sandy soil who prefer producing carrots, we can use the relative frequency formula:
\[ \text{Relative frequency} = \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}} \]
In this case, the number of farmers with sandy soil who prefer carrots is 120, and the total number of farmers with sandy soil is 170.
Now, we can calculate the relative frequency:
\[ \text{Relative frequency} = \frac{120}{170} \]
Calculating that gives:
\[ \text{Relative frequency} \approx 0.7058823529 \]
To convert this to a percentage, we multiply by 100:
\[ 0.7058823529 \times 100 \approx 70.58823529% \]
Rounding this to the nearest tenth, we get:
\[ 70.6% \]
Thus, the percentage chance that farmers with sandy soil prefer to grow carrots is 70.6%.