Finding the Fourth Proportional to 1,385.78, 1,911.84 and 788.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.78 : 1,911.84 = 788.18 : x
2. Step 2: Convert to fraction form
   1,385.78/1,911.84 = 788.18/x
3. Step 3: Cross multiply
   1,385.78x = 1,911.84 × 788.18
4. Step 4: Simplify right side
   1,385.78x = 1,506,864.49
5. Step 5: Solve for x
   x = 1,506,864.49/1,385.78
6. Step 6: Final answer
   x = 1,087.38