Finding the Fourth Proportional to 1,398.72, 1,930.32 and 777.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.72 : 1,930.32 = 777.76 : x
2. Step 2: Convert to fraction form
   1,398.72/1,930.32 = 777.76/x
3. Step 3: Cross multiply
   1,398.72x = 1,930.32 × 777.76
4. Step 4: Simplify right side
   1,398.72x = 1,501,325.68
5. Step 5: Solve for x
   x = 1,501,325.68/1,398.72
6. Step 6: Final answer
   x = 1,073.36