Finding the Fourth Proportional to 1,018.65, 1,404.50 and 861

Step by Step Solution

1. Step 1: Write the proportion equation
   1,018.65 : 1,404.50 = 861 : x
2. Step 2: Convert to fraction form
   1,018.65/1,404.50 = 861/x
3. Step 3: Cross multiply
   1,018.65x = 1,404.50 × 861
4. Step 4: Simplify right side
   1,018.65x = 1,209,274.50
5. Step 5: Solve for x
   x = 1,209,274.50/1,018.65
6. Step 6: Final answer
   x = 1,187.14