Finding the Fourth Proportional to 31,138.72, 42,956.88 and 21,064

Step by Step Solution

1. Step 1: Write the proportion equation
   31,138.72 : 42,956.88 = 21,064 : x
2. Step 2: Convert to fraction form
   31,138.72/42,956.88 = 21,064/x
3. Step 3: Cross multiply
   31,138.72x = 42,956.88 × 21,064
4. Step 4: Simplify right side
   31,138.72x = 904,843,720.32
5. Step 5: Solve for x
   x = 904,843,720.32/31,138.72
6. Step 6: Final answer
   x = 29,058.48