Finding the Fourth Proportional to 1,390.71, 1,918.84 and 866.37

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.71 : 1,918.84 = 866.37 : x
2. Step 2: Convert to fraction form
   1,390.71/1,918.84 = 866.37/x
3. Step 3: Cross multiply
   1,390.71x = 1,918.84 × 866.37
4. Step 4: Simplify right side
   1,390.71x = 1,662,425.41
5. Step 5: Solve for x
   x = 1,662,425.41/1,390.71
6. Step 6: Final answer
   x = 1,195.38