Finding the Third Proportional to 4,688.72 and 9,985.78

Step by Step Solution

1. Step 1: Write the proportion equation
   4,688.72 : 9,985.78 = 9,985.78 : x
2. Step 2: Convert to fraction form
   4,688.72/9,985.78 = 9,985.78/x
3. Step 3: Cross multiply
   4,688.72x = 9,985.78 × 9,985.78
4. Step 4: Simplify right side
   4,688.72x = 99,715,827.17
5. Step 5: Solve for x
   x = 99,715,827.17/4,688.72
6. Step 6: Final answer
   x = 21,267.18