Finding the Fourth Proportional to 7,128.45, 10,001.70 and 7,128.45

Step by Step Solution

1. Step 1: Write the proportion equation
   7,128.45 : 10,001.70 = 7,128.45 : x
2. Step 2: Convert to fraction form
   7,128.45/10,001.70 = 7,128.45/x
3. Step 3: Cross multiply
   7,128.45x = 10,001.70 × 7,128.45
4. Step 4: Simplify right side
   7,128.45x = 71,296,618.37
5. Step 5: Solve for x
   x = 71,296,618.37/7,128.45
6. Step 6: Final answer
   x = 10,001.70