Finding the Fourth Proportional to 1,385.12, 1,911.60 and 1,035.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.12 : 1,911.60 = 1,035.20 : x
2. Step 2: Convert to fraction form
   1,385.12/1,911.60 = 1,035.20/x
3. Step 3: Cross multiply
   1,385.12x = 1,911.60 × 1,035.20
4. Step 4: Simplify right side
   1,385.12x = 1,978,888.32
5. Step 5: Solve for x
   x = 1,978,888.32/1,385.12
6. Step 6: Final answer
   x = 1,428.68