Finding the Fourth Proportional to 2,072.18, 3,109.28 and 840.47

Step by Step Solution

1. Step 1: Write the proportion equation
   2,072.18 : 3,109.28 = 840.47 : x
2. Step 2: Convert to fraction form
   2,072.18/3,109.28 = 840.47/x
3. Step 3: Cross multiply
   2,072.18x = 3,109.28 × 840.47
4. Step 4: Simplify right side
   2,072.18x = 2,613,256.56
5. Step 5: Solve for x
   x = 2,613,256.56/2,072.18
6. Step 6: Final answer
   x = 1,261.11