Finding the Fourth Proportional to 39,761.31, 54,870.72 and 21,858.15

Step by Step Solution

1. Step 1: Write the proportion equation
   39,761.31 : 54,870.72 = 21,858.15 : x
2. Step 2: Convert to fraction form
   39,761.31/54,870.72 = 21,858.15/x
3. Step 3: Cross multiply
   39,761.31x = 54,870.72 × 21,858.15
4. Step 4: Simplify right side
   39,761.31x = 1,199,372,428.37
5. Step 5: Solve for x
   x = 1,199,372,428.37/39,761.31
6. Step 6: Final answer
   x = 30,164.31