Finding the Fourth Proportional to 21,477.86, 29,636.96 and 12,985.10

Step by Step Solution

1. Step 1: Write the proportion equation
   21,477.86 : 29,636.96 = 12,985.10 : x
2. Step 2: Convert to fraction form
   21,477.86/29,636.96 = 12,985.10/x
3. Step 3: Cross multiply
   21,477.86x = 29,636.96 × 12,985.10
4. Step 4: Simplify right side
   21,477.86x = 384,838,889.30
5. Step 5: Solve for x
   x = 384,838,889.30/21,477.86
6. Step 6: Final answer
   x = 17,917.93