Finding the Fourth Proportional to 40,128.08, 55,375.21 and 21,978.51

Step by Step Solution

1. Step 1: Write the proportion equation
   40,128.08 : 55,375.21 = 21,978.51 : x
2. Step 2: Convert to fraction form
   40,128.08/55,375.21 = 21,978.51/x
3. Step 3: Cross multiply
   40,128.08x = 55,375.21 × 21,978.51
4. Step 4: Simplify right side
   40,128.08x = 1,217,064,426.55
5. Step 5: Solve for x
   x = 1,217,064,426.55/40,128.08
6. Step 6: Final answer
   x = 30,329.50