Finding the Fourth Proportional to 1,112.78, 1,669.72 and 766.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,112.78 : 1,669.72 = 766.64 : x
2. Step 2: Convert to fraction form
   1,112.78/1,669.72 = 766.64/x
3. Step 3: Cross multiply
   1,112.78x = 1,669.72 × 766.64
4. Step 4: Simplify right side
   1,112.78x = 1,280,074.14
5. Step 5: Solve for x
   x = 1,280,074.14/1,112.78
6. Step 6: Final answer
   x = 1,150.34