Finding the Fourth Proportional to 1,090.78, 1,505.24 and 618.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,090.78 : 1,505.24 = 618.72 : x
2. Step 2: Convert to fraction form
   1,090.78/1,505.24 = 618.72/x
3. Step 3: Cross multiply
   1,090.78x = 1,505.24 × 618.72
4. Step 4: Simplify right side
   1,090.78x = 931,319.88
5. Step 5: Solve for x
   x = 931,319.88/1,090.78
6. Step 6: Final answer
   x = 853.81