Finding the Fourth Proportional to 1,390.53, 1,918.98 and 866.46

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.53 : 1,918.98 = 866.46 : x
2. Step 2: Convert to fraction form
   1,390.53/1,918.98 = 866.46/x
3. Step 3: Cross multiply
   1,390.53x = 1,918.98 × 866.46
4. Step 4: Simplify right side
   1,390.53x = 1,662,719.41
5. Step 5: Solve for x
   x = 1,662,719.41/1,390.53
6. Step 6: Final answer
   x = 1,195.75