Finding the Fourth Proportional to 1,355.10, 1,870.02 and 765.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.10 : 1,870.02 = 765.78 : x
2. Step 2: Convert to fraction form
   1,355.10/1,870.02 = 765.78/x
3. Step 3: Cross multiply
   1,355.10x = 1,870.02 × 765.78
4. Step 4: Simplify right side
   1,355.10x = 1,432,023.92
5. Step 5: Solve for x
   x = 1,432,023.92/1,355.10
6. Step 6: Final answer
   x = 1,056.77