Finding the Fourth Proportional to 1,388.82, 2,085.45 and 869.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.82 : 2,085.45 = 869.88 : x
2. Step 2: Convert to fraction form
   1,388.82/2,085.45 = 869.88/x
3. Step 3: Cross multiply
   1,388.82x = 2,085.45 × 869.88
4. Step 4: Simplify right side
   1,388.82x = 1,814,091.25
5. Step 5: Solve for x
   x = 1,814,091.25/1,388.82
6. Step 6: Final answer
   x = 1,306.21