Finding the Fourth Proportional to 1,386.39, 2,080.25 and 866.25

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.39 : 2,080.25 = 866.25 : x
2. Step 2: Convert to fraction form
   1,386.39/2,080.25 = 866.25/x
3. Step 3: Cross multiply
   1,386.39x = 2,080.25 × 866.25
4. Step 4: Simplify right side
   1,386.39x = 1,802,016.56
5. Step 5: Solve for x
   x = 1,802,016.56/1,386.39
6. Step 6: Final answer
   x = 1,299.79