Finding the Fourth Proportional to 1,231.26, 1,698.72 and 765.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,231.26 : 1,698.72 = 765.78 : x
2. Step 2: Convert to fraction form
   1,231.26/1,698.72 = 765.78/x
3. Step 3: Cross multiply
   1,231.26x = 1,698.72 × 765.78
4. Step 4: Simplify right side
   1,231.26x = 1,300,845.80
5. Step 5: Solve for x
   x = 1,300,845.80/1,231.26
6. Step 6: Final answer
   x = 1,056.52