Finding the Fourth Proportional to 1,380.29, 1,904.78 and 790.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.29 : 1,904.78 = 790.81 : x
2. Step 2: Convert to fraction form
   1,380.29/1,904.78 = 790.81/x
3. Step 3: Cross multiply
   1,380.29x = 1,904.78 × 790.81
4. Step 4: Simplify right side
   1,380.29x = 1,506,309.55
5. Step 5: Solve for x
   x = 1,506,309.55/1,380.29
6. Step 6: Final answer
   x = 1,091.30