Finding the Fourth Proportional to 1,385.40, 1,911.89 and 787.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.40 : 1,911.89 = 787.99 : x
2. Step 2: Convert to fraction form
   1,385.40/1,911.89 = 787.99/x
3. Step 3: Cross multiply
   1,385.40x = 1,911.89 × 787.99
4. Step 4: Simplify right side
   1,385.40x = 1,506,546.26
5. Step 5: Solve for x
   x = 1,506,546.26/1,385.40
6. Step 6: Final answer
   x = 1,087.44