Finding the Fourth Proportional to 1,398.69, 1,929.15 and 919.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.69 : 1,929.15 = 919.89 : x
2. Step 2: Convert to fraction form
   1,398.69/1,929.15 = 919.89/x
3. Step 3: Cross multiply
   1,398.69x = 1,929.15 × 919.89
4. Step 4: Simplify right side
   1,398.69x = 1,774,605.79
5. Step 5: Solve for x
   x = 1,774,605.79/1,398.69
6. Step 6: Final answer
   x = 1,268.76