Finding the Fourth Proportional to 1,003.05, 1,505.05 and 386.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,003.05 : 1,505.05 = 386.98 : x
2. Step 2: Convert to fraction form
   1,003.05/1,505.05 = 386.98/x
3. Step 3: Cross multiply
   1,003.05x = 1,505.05 × 386.98
4. Step 4: Simplify right side
   1,003.05x = 582,419.52
5. Step 5: Solve for x
   x = 582,419.52/1,003.05
6. Step 6: Final answer
   x = 580.65