Finding the Fourth Proportional to 12,816.70, 17,686.55 and 7,151.15

Step by Step Solution

1. Step 1: Write the proportion equation
   12,816.70 : 17,686.55 = 7,151.15 : x
2. Step 2: Convert to fraction form
   12,816.70/17,686.55 = 7,151.15/x
3. Step 3: Cross multiply
   12,816.70x = 17,686.55 × 7,151.15
4. Step 4: Simplify right side
   12,816.70x = 126,479,136.28
5. Step 5: Solve for x
   x = 126,479,136.28/12,816.70
6. Step 6: Final answer
   x = 9,868.31