Finding the Fourth Proportional to 1,380.06, 1,903.64 and 820.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.06 : 1,903.64 = 820.15 : x
2. Step 2: Convert to fraction form
   1,380.06/1,903.64 = 820.15/x
3. Step 3: Cross multiply
   1,380.06x = 1,903.64 × 820.15
4. Step 4: Simplify right side
   1,380.06x = 1,561,261.49
5. Step 5: Solve for x
   x = 1,561,261.49/1,380.06
6. Step 6: Final answer
   x = 1,131.30