Finding the Fourth Proportional to 13,858.80, 20,789.82 and 5,091.72

Step by Step Solution

1. Step 1: Write the proportion equation
   13,858.80 : 20,789.82 = 5,091.72 : x
2. Step 2: Convert to fraction form
   13,858.80/20,789.82 = 5,091.72/x
3. Step 3: Cross multiply
   13,858.80x = 20,789.82 × 5,091.72
4. Step 4: Simplify right side
   13,858.80x = 105,855,942.29
5. Step 5: Solve for x
   x = 105,855,942.29/13,858.80
6. Step 6: Final answer
   x = 7,638.18