Finding the Fourth Proportional to 40,139.49, 55,392.96 and 21,990.69

Step by Step Solution

1. Step 1: Write the proportion equation
   40,139.49 : 55,392.96 = 21,990.69 : x
2. Step 2: Convert to fraction form
   40,139.49/55,392.96 = 21,990.69/x
3. Step 3: Cross multiply
   40,139.49x = 55,392.96 × 21,990.69
4. Step 4: Simplify right side
   40,139.49x = 1,218,129,411.54
5. Step 5: Solve for x
   x = 1,218,129,411.54/40,139.49
6. Step 6: Final answer
   x = 30,347.41