Finding the Fourth Proportional to 1,385.92, 1,912.57 and 788.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.92 : 1,912.57 = 788.34 : x
2. Step 2: Convert to fraction form
   1,385.92/1,912.57 = 788.34/x
3. Step 3: Cross multiply
   1,385.92x = 1,912.57 × 788.34
4. Step 4: Simplify right side
   1,385.92x = 1,507,748.68
5. Step 5: Solve for x
   x = 1,507,748.68/1,385.92
6. Step 6: Final answer
   x = 1,087.91