Finding the Fourth Proportional to 1,117.78, 1,674.81 and 386.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,117.78 : 1,674.81 = 386.96 : x
2. Step 2: Convert to fraction form
   1,117.78/1,674.81 = 386.96/x
3. Step 3: Cross multiply
   1,117.78x = 1,674.81 × 386.96
4. Step 4: Simplify right side
   1,117.78x = 648,076.10
5. Step 5: Solve for x
   x = 648,076.10/1,117.78
6. Step 6: Final answer
   x = 579.79