Finding the Fourth Proportional to 1,355.40, 1,870.38 and 765.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.40 : 1,870.38 = 765.90 : x
2. Step 2: Convert to fraction form
   1,355.40/1,870.38 = 765.90/x
3. Step 3: Cross multiply
   1,355.40x = 1,870.38 × 765.90
4. Step 4: Simplify right side
   1,355.40x = 1,432,524.04
5. Step 5: Solve for x
   x = 1,432,524.04/1,355.40
6. Step 6: Final answer
   x = 1,056.90