Finding the Fourth Proportional to 1,308.78, 1,960.10 and 613.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,308.78 : 1,960.10 = 613.96 : x
2. Step 2: Convert to fraction form
   1,308.78/1,960.10 = 613.96/x
3. Step 3: Cross multiply
   1,308.78x = 1,960.10 × 613.96
4. Step 4: Simplify right side
   1,308.78x = 1,203,415.03
5. Step 5: Solve for x
   x = 1,203,415.03/1,308.78
6. Step 6: Final answer
   x = 919.49