Finding the Fourth Proportional to 1,290.08, 1,780.32 and 766.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.08 : 1,780.32 = 766.56 : x
2. Step 2: Convert to fraction form
   1,290.08/1,780.32 = 766.56/x
3. Step 3: Cross multiply
   1,290.08x = 1,780.32 × 766.56
4. Step 4: Simplify right side
   1,290.08x = 1,364,722.10
5. Step 5: Solve for x
   x = 1,364,722.10/1,290.08
6. Step 6: Final answer
   x = 1,057.86