Finding the Fourth Proportional to 1,638.89, 2,261.72 and 930.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,638.89 : 2,261.72 = 930.72 : x
2. Step 2: Convert to fraction form
   1,638.89/2,261.72 = 930.72/x
3. Step 3: Cross multiply
   1,638.89x = 2,261.72 × 930.72
4. Step 4: Simplify right side
   1,638.89x = 2,105,023.38
5. Step 5: Solve for x
   x = 2,105,023.38/1,638.89
6. Step 6: Final answer
   x = 1,284.42