Finding the Fourth Proportional to 21,781.76, 32,631.56 and 12,870.52

Step by Step Solution

1. Step 1: Write the proportion equation
   21,781.76 : 32,631.56 = 12,870.52 : x
2. Step 2: Convert to fraction form
   21,781.76/32,631.56 = 12,870.52/x
3. Step 3: Cross multiply
   21,781.76x = 32,631.56 × 12,870.52
4. Step 4: Simplify right side
   21,781.76x = 419,985,145.61
5. Step 5: Solve for x
   x = 419,985,145.61/21,781.76
6. Step 6: Final answer
   x = 19,281.51