Finding the Fourth Proportional to 9,145.50, 12,619.78 and 5,165.77

Step by Step Solution

1. Step 1: Write the proportion equation
   9,145.50 : 12,619.78 = 5,165.77 : x
2. Step 2: Convert to fraction form
   9,145.50/12,619.78 = 5,165.77/x
3. Step 3: Cross multiply
   9,145.50x = 12,619.78 × 5,165.77
4. Step 4: Simplify right side
   9,145.50x = 65,190,880.93
5. Step 5: Solve for x
   x = 65,190,880.93/9,145.50
6. Step 6: Final answer
   x = 7,128.19