Finding the Fourth Proportional to 1,387.56, 1,914.72 and 766.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.56 : 1,914.72 = 766.56 : x
2. Step 2: Convert to fraction form
   1,387.56/1,914.72 = 766.56/x
3. Step 3: Cross multiply
   1,387.56x = 1,914.72 × 766.56
4. Step 4: Simplify right side
   1,387.56x = 1,467,747.76
5. Step 5: Solve for x
   x = 1,467,747.76/1,387.56
6. Step 6: Final answer
   x = 1,057.79