Finding the Fourth Proportional to 20,870.66, 31,298.79 and 13,887.42

Step by Step Solution

1. Step 1: Write the proportion equation
   20,870.66 : 31,298.79 = 13,887.42 : x
2. Step 2: Convert to fraction form
   20,870.66/31,298.79 = 13,887.42/x
3. Step 3: Cross multiply
   20,870.66x = 31,298.79 × 13,887.42
4. Step 4: Simplify right side
   20,870.66x = 434,659,442.22
5. Step 5: Solve for x
   x = 434,659,442.22/20,870.66
6. Step 6: Final answer
   x = 20,826.34