Finding the Fourth Proportional to 1,398.78, 1,929.96 and 933.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.78 : 1,929.96 = 933.12 : x
2. Step 2: Convert to fraction form
   1,398.78/1,929.96 = 933.12/x
3. Step 3: Cross multiply
   1,398.78x = 1,929.96 × 933.12
4. Step 4: Simplify right side
   1,398.78x = 1,800,884.28
5. Step 5: Solve for x
   x = 1,800,884.28/1,398.78
6. Step 6: Final answer
   x = 1,287.47