Finding the Fourth Proportional to 21,691.67, 29,931.32 and 12,742.07

Step by Step Solution

1. Step 1: Write the proportion equation
   21,691.67 : 29,931.32 = 12,742.07 : x
2. Step 2: Convert to fraction form
   21,691.67/29,931.32 = 12,742.07/x
3. Step 3: Cross multiply
   21,691.67x = 29,931.32 × 12,742.07
4. Step 4: Simplify right side
   21,691.67x = 381,386,856.83
5. Step 5: Solve for x
   x = 381,386,856.83/21,691.67
6. Step 6: Final answer
   x = 17,582.18