Finding the Fourth Proportional to 31,128.44, 42,971.16 and 21,087.37

Step by Step Solution

1. Step 1: Write the proportion equation
   31,128.44 : 42,971.16 = 21,087.37 : x
2. Step 2: Convert to fraction form
   31,128.44/42,971.16 = 21,087.37/x
3. Step 3: Cross multiply
   31,128.44x = 42,971.16 × 21,087.37
4. Step 4: Simplify right side
   31,128.44x = 906,148,644.81
5. Step 5: Solve for x
   x = 906,148,644.81/31,128.44
6. Step 6: Final answer
   x = 29,110.00