Finding the Fourth Proportional to 1,355.68, 1,870.72 and 766.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.68 : 1,870.72 = 766.20 : x
2. Step 2: Convert to fraction form
   1,355.68/1,870.72 = 766.20/x
3. Step 3: Cross multiply
   1,355.68x = 1,870.72 × 766.20
4. Step 4: Simplify right side
   1,355.68x = 1,433,345.66
5. Step 5: Solve for x
   x = 1,433,345.66/1,355.68
6. Step 6: Final answer
   x = 1,057.29