Finding the Fourth Proportional to 14,131.67, 21,164.69 and 13,639.59

Step by Step Solution

1. Step 1: Write the proportion equation
   14,131.67 : 21,164.69 = 13,639.59 : x
2. Step 2: Convert to fraction form
   14,131.67/21,164.69 = 13,639.59/x
3. Step 3: Cross multiply
   14,131.67x = 21,164.69 × 13,639.59
4. Step 4: Simplify right side
   14,131.67x = 288,677,728.18
5. Step 5: Solve for x
   x = 288,677,728.18/14,131.67
6. Step 6: Final answer
   x = 20,427.72