Finding the Fourth Proportional to 1,155.42, 1,729.98 and 788.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,155.42 : 1,729.98 = 788.40 : x
2. Step 2: Convert to fraction form
   1,155.42/1,729.98 = 788.40/x
3. Step 3: Cross multiply
   1,155.42x = 1,729.98 × 788.40
4. Step 4: Simplify right side
   1,155.42x = 1,363,916.23
5. Step 5: Solve for x
   x = 1,363,916.23/1,155.42
6. Step 6: Final answer
   x = 1,180.45