Finding the Fourth Proportional to 1,379.78, 1,903.96 and 820.07

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.78 : 1,903.96 = 820.07 : x
2. Step 2: Convert to fraction form
   1,379.78/1,903.96 = 820.07/x
3. Step 3: Cross multiply
   1,379.78x = 1,903.96 × 820.07
4. Step 4: Simplify right side
   1,379.78x = 1,561,385.22
5. Step 5: Solve for x
   x = 1,561,385.22/1,379.78
6. Step 6: Final answer
   x = 1,131.62