Finding the Fourth Proportional to 9,985.78, 13,680.50 and 9,611.92

Step by Step Solution

1. Step 1: Write the proportion equation
   9,985.78 : 13,680.50 = 9,611.92 : x
2. Step 2: Convert to fraction form
   9,985.78/13,680.50 = 9,611.92/x
3. Step 3: Cross multiply
   9,985.78x = 13,680.50 × 9,611.92
4. Step 4: Simplify right side
   9,985.78x = 131,495,871.56
5. Step 5: Solve for x
   x = 131,495,871.56/9,985.78
6. Step 6: Final answer
   x = 13,168.31