Finding the Fourth Proportional to 1,076.58, 1,612.38 and 642.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,076.58 : 1,612.38 = 642.78 : x
2. Step 2: Convert to fraction form
   1,076.58/1,612.38 = 642.78/x
3. Step 3: Cross multiply
   1,076.58x = 1,612.38 × 642.78
4. Step 4: Simplify right side
   1,076.58x = 1,036,405.62
5. Step 5: Solve for x
   x = 1,036,405.62/1,076.58
6. Step 6: Final answer
   x = 962.68