Finding the Fourth Proportional to 1,290.12, 1,780.50 and 766.14

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.12 : 1,780.50 = 766.14 : x
2. Step 2: Convert to fraction form
   1,290.12/1,780.50 = 766.14/x
3. Step 3: Cross multiply
   1,290.12x = 1,780.50 × 766.14
4. Step 4: Simplify right side
   1,290.12x = 1,364,112.27
5. Step 5: Solve for x
   x = 1,364,112.27/1,290.12
6. Step 6: Final answer
   x = 1,057.35