Finding the Fourth Proportional to 1,200.78, 1,656.61 and 886.79

Step by Step Solution

1. Step 1: Write the proportion equation
   1,200.78 : 1,656.61 = 886.79 : x
2. Step 2: Convert to fraction form
   1,200.78/1,656.61 = 886.79/x
3. Step 3: Cross multiply
   1,200.78x = 1,656.61 × 886.79
4. Step 4: Simplify right side
   1,200.78x = 1,469,064.94
5. Step 5: Solve for x
   x = 1,469,064.94/1,200.78
6. Step 6: Final answer
   x = 1,223.42