Finding the Fourth Proportional to 3,456.80, 5,185.12 and 991.56

Step by Step Solution

1. Step 1: Write the proportion equation
   3,456.80 : 5,185.12 = 991.56 : x
2. Step 2: Convert to fraction form
   3,456.80/5,185.12 = 991.56/x
3. Step 3: Cross multiply
   3,456.80x = 5,185.12 × 991.56
4. Step 4: Simplify right side
   3,456.80x = 5,141,357.59
5. Step 5: Solve for x
   x = 5,141,357.59/3,456.80
6. Step 6: Final answer
   x = 1,487.32