Finding the Fourth Proportional to 31,146.65, 42,967.43 and 20,386.78

Step by Step Solution

1. Step 1: Write the proportion equation
   31,146.65 : 42,967.43 = 20,386.78 : x
2. Step 2: Convert to fraction form
   31,146.65/42,967.43 = 20,386.78/x
3. Step 3: Cross multiply
   31,146.65x = 42,967.43 × 20,386.78
4. Step 4: Simplify right side
   31,146.65x = 875,967,333.22
5. Step 5: Solve for x
   x = 875,967,333.22/31,146.65
6. Step 6: Final answer
   x = 28,123.97