Finding the Fourth Proportional to 1,238.78, 1,858.17 and 661.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.78 : 1,858.17 = 661.52 : x
2. Step 2: Convert to fraction form
   1,238.78/1,858.17 = 661.52/x
3. Step 3: Cross multiply
   1,238.78x = 1,858.17 × 661.52
4. Step 4: Simplify right side
   1,238.78x = 1,229,216.62
5. Step 5: Solve for x
   x = 1,229,216.62/1,238.78
6. Step 6: Final answer
   x = 992.28