Finding the Fourth Proportional to 31,089.33, 42,888.56 and 21,021.30

Step by Step Solution

1. Step 1: Write the proportion equation
   31,089.33 : 42,888.56 = 21,021.30 : x
2. Step 2: Convert to fraction form
   31,089.33/42,888.56 = 21,021.30/x
3. Step 3: Cross multiply
   31,089.33x = 42,888.56 × 21,021.30
4. Step 4: Simplify right side
   31,089.33x = 901,573,181.22
5. Step 5: Solve for x
   x = 901,573,181.22/31,089.33
6. Step 6: Final answer
   x = 28,999.44