Finding the Fourth Proportional to 2,085.17, 3,129.30 and 989.55

Step by Step Solution

1. Step 1: Write the proportion equation
   2,085.17 : 3,129.30 = 989.55 : x
2. Step 2: Convert to fraction form
   2,085.17/3,129.30 = 989.55/x
3. Step 3: Cross multiply
   2,085.17x = 3,129.30 × 989.55
4. Step 4: Simplify right side
   2,085.17x = 3,096,598.82
5. Step 5: Solve for x
   x = 3,096,598.82/2,085.17
6. Step 6: Final answer
   x = 1,485.06