Finding the Fourth Proportional to 1,355.19, 1,870.17 and 765.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.19 : 1,870.17 = 765.78 : x
2. Step 2: Convert to fraction form
   1,355.19/1,870.17 = 765.78/x
3. Step 3: Cross multiply
   1,355.19x = 1,870.17 × 765.78
4. Step 4: Simplify right side
   1,355.19x = 1,432,125.60
5. Step 5: Solve for x
   x = 1,432,125.60/1,355.19
6. Step 6: Final answer
   x = 1,056.77