Finding the Fourth Proportional to 1,355.20, 1,870.03 and 765.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.20 : 1,870.03 = 765.72 : x
2. Step 2: Convert to fraction form
   1,355.20/1,870.03 = 765.72/x
3. Step 3: Cross multiply
   1,355.20x = 1,870.03 × 765.72
4. Step 4: Simplify right side
   1,355.20x = 1,431,919.37
5. Step 5: Solve for x
   x = 1,431,919.37/1,355.20
6. Step 6: Final answer
   x = 1,056.61