Finding the Fourth Proportional to 1,387.89, 1,914.24 and 1,107.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.89 : 1,914.24 = 1,107.78 : x
2. Step 2: Convert to fraction form
   1,387.89/1,914.24 = 1,107.78/x
3. Step 3: Cross multiply
   1,387.89x = 1,914.24 × 1,107.78
4. Step 4: Simplify right side
   1,387.89x = 2,120,556.79
5. Step 5: Solve for x
   x = 2,120,556.79/1,387.89
6. Step 6: Final answer
   x = 1,527.90