Finding the Fourth Proportional to 1,390.34, 1,918.50 and 866.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.34 : 1,918.50 = 866.18 : x
2. Step 2: Convert to fraction form
   1,390.34/1,918.50 = 866.18/x
3. Step 3: Cross multiply
   1,390.34x = 1,918.50 × 866.18
4. Step 4: Simplify right side
   1,390.34x = 1,661,766.33
5. Step 5: Solve for x
   x = 1,661,766.33/1,390.34
6. Step 6: Final answer
   x = 1,195.22