Finding the Fourth Proportional to 1,200.07, 1,655.15 and 780.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,200.07 : 1,655.15 = 780.55 : x
2. Step 2: Convert to fraction form
   1,200.07/1,655.15 = 780.55/x
3. Step 3: Cross multiply
   1,200.07x = 1,655.15 × 780.55
4. Step 4: Simplify right side
   1,200.07x = 1,291,927.33
5. Step 5: Solve for x
   x = 1,291,927.33/1,200.07
6. Step 6: Final answer
   x = 1,076.54