Finding the Fourth Proportional to 1,116.72, 1,675.31 and 386.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,116.72 : 1,675.31 = 386.20 : x
2. Step 2: Convert to fraction form
   1,116.72/1,675.31 = 386.20/x
3. Step 3: Cross multiply
   1,116.72x = 1,675.31 × 386.20
4. Step 4: Simplify right side
   1,116.72x = 647,004.72
5. Step 5: Solve for x
   x = 647,004.72/1,116.72
6. Step 6: Final answer
   x = 579.38