Finding the Fourth Proportional to 1,279.34, 1,765.78 and 813.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,279.34 : 1,765.78 = 813.50 : x
2. Step 2: Convert to fraction form
   1,279.34/1,765.78 = 813.50/x
3. Step 3: Cross multiply
   1,279.34x = 1,765.78 × 813.50
4. Step 4: Simplify right side
   1,279.34x = 1,436,462.03
5. Step 5: Solve for x
   x = 1,436,462.03/1,279.34
6. Step 6: Final answer
   x = 1,122.81