Finding the Fourth Proportional to 1,389.09, 1,917.69 and 885.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.09 : 1,917.69 = 885.45 : x
2. Step 2: Convert to fraction form
   1,389.09/1,917.69 = 885.45/x
3. Step 3: Cross multiply
   1,389.09x = 1,917.69 × 885.45
4. Step 4: Simplify right side
   1,389.09x = 1,698,018.61
5. Step 5: Solve for x
   x = 1,698,018.61/1,389.09
6. Step 6: Final answer
   x = 1,222.40