Finding the Fourth Proportional to 1,380.18, 1,904.71 and 790.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.18 : 1,904.71 = 790.72 : x
2. Step 2: Convert to fraction form
   1,380.18/1,904.71 = 790.72/x
3. Step 3: Cross multiply
   1,380.18x = 1,904.71 × 790.72
4. Step 4: Simplify right side
   1,380.18x = 1,506,085.55
5. Step 5: Solve for x
   x = 1,506,085.55/1,380.18
6. Step 6: Final answer
   x = 1,091.22