To find the number of red cars in the parking lot, we can start by using the given ratio of blue to red cars, which is 11:6.
Let:
- \( b \) = number of blue cars
- \( r \) = number of red cars
From the problem, we know:
- \( b = 317 \)
- The ratio of blue to red cars can be expressed as:
\[ \frac{b}{r} = \frac{11}{6} \]
We can rearrange this ratio to solve for \( r \):
\[ r = \frac{6}{11} \times b \]
Now we can substitute the value of \( b \) into the equation:
\[ r = \frac{6}{11} \times 317 \]
Calculating this gives:
\[ r = \frac{6 \times 317}{11} \] \[ = \frac{1902}{11} \] \[ \approx 172.909 \]
Rounding \( 172.909 \) to the nearest whole number gives us \( 173 \).
So, the number of red cars in the parking lot is 173.