Finding the Fourth Proportional to 1,308.89, 1,807.87 and 978.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,308.89 : 1,807.87 = 978.79 : x
2. Step 2: Convert to fraction form
   1,308.89/1,807.87 = 978.79/x
3. Step 3: Cross multiply
   1,308.89x = 1,807.87 × 978.79
4. Step 4: Simplify right side
   1,308.89x = 1,769,517.26
5. Step 5: Solve for x
   x = 1,769,517.26/1,308.89
6. Step 6: Final answer
   x = 1,351.92