Finding the Fourth Proportional to 10,640.17, 15,957.15 and 7,128.01

Step by Step Solution

1. Step 1: Write the proportion equation
   10,640.17 : 15,957.15 = 7,128.01 : x
2. Step 2: Convert to fraction form
   10,640.17/15,957.15 = 7,128.01/x
3. Step 3: Cross multiply
   10,640.17x = 15,957.15 × 7,128.01
4. Step 4: Simplify right side
   10,640.17x = 113,742,724.77
5. Step 5: Solve for x
   x = 113,742,724.77/10,640.17
6. Step 6: Final answer
   x = 10,689.93