Finding the Fourth Proportional to 1,389.07, 1,918.34 and 1,191.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.07 : 1,918.34 = 1,191.43 : x
2. Step 2: Convert to fraction form
   1,389.07/1,918.34 = 1,191.43/x
3. Step 3: Cross multiply
   1,389.07x = 1,918.34 × 1,191.43
4. Step 4: Simplify right side
   1,389.07x = 2,285,567.83
5. Step 5: Solve for x
   x = 2,285,567.83/1,389.07
6. Step 6: Final answer
   x = 1,645.39