Finding the Fourth Proportional to 1,085.78, 1,498.62 and 687.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.78 : 1,498.62 = 687.42 : x
2. Step 2: Convert to fraction form
   1,085.78/1,498.62 = 687.42/x
3. Step 3: Cross multiply
   1,085.78x = 1,498.62 × 687.42
4. Step 4: Simplify right side
   1,085.78x = 1,030,181.36
5. Step 5: Solve for x
   x = 1,030,181.36/1,085.78
6. Step 6: Final answer
   x = 948.79