Finding the Fourth Proportional to 1,209.32, 1,815.12 and 776.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.32 : 1,815.12 = 776.72 : x
2. Step 2: Convert to fraction form
   1,209.32/1,815.12 = 776.72/x
3. Step 3: Cross multiply
   1,209.32x = 1,815.12 × 776.72
4. Step 4: Simplify right side
   1,209.32x = 1,409,840.01
5. Step 5: Solve for x
   x = 1,409,840.01/1,209.32
6. Step 6: Final answer
   x = 1,165.81