Finding the Fourth Proportional to 12,985.76, 17,916.72 and 8,742.80

Step by Step Solution

1. Step 1: Write the proportion equation
   12,985.76 : 17,916.72 = 8,742.80 : x
2. Step 2: Convert to fraction form
   12,985.76/17,916.72 = 8,742.80/x
3. Step 3: Cross multiply
   12,985.76x = 17,916.72 × 8,742.80
4. Step 4: Simplify right side
   12,985.76x = 156,642,299.62
5. Step 5: Solve for x
   x = 156,642,299.62/12,985.76
6. Step 6: Final answer
   x = 12,062.62