Finding the Fourth Proportional to 1,386.08, 1,912.72 and 765.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.08 : 1,912.72 = 765.12 : x
2. Step 2: Convert to fraction form
   1,386.08/1,912.72 = 765.12/x
3. Step 3: Cross multiply
   1,386.08x = 1,912.72 × 765.12
4. Step 4: Simplify right side
   1,386.08x = 1,463,460.33
5. Step 5: Solve for x
   x = 1,463,460.33/1,386.08
6. Step 6: Final answer
   x = 1,055.83