Finding the Fourth Proportional to 13,021.54, 17,970.06 and 7,715.50

Step by Step Solution

1. Step 1: Write the proportion equation
   13,021.54 : 17,970.06 = 7,715.50 : x
2. Step 2: Convert to fraction form
   13,021.54/17,970.06 = 7,715.50/x
3. Step 3: Cross multiply
   13,021.54x = 17,970.06 × 7,715.50
4. Step 4: Simplify right side
   13,021.54x = 138,647,997.93
5. Step 5: Solve for x
   x = 138,647,997.93/13,021.54
6. Step 6: Final answer
   x = 10,647.59