Finding the Fourth Proportional to 20,870.79, 28,801.29 and 12,910.92

Step by Step Solution

1. Step 1: Write the proportion equation
   20,870.79 : 28,801.29 = 12,910.92 : x
2. Step 2: Convert to fraction form
   20,870.79/28,801.29 = 12,910.92/x
3. Step 3: Cross multiply
   20,870.79x = 28,801.29 × 12,910.92
4. Step 4: Simplify right side
   20,870.79x = 371,851,151.09
5. Step 5: Solve for x
   x = 371,851,151.09/20,870.79
6. Step 6: Final answer
   x = 17,816.82