Finding the Fourth Proportional to 1,399.62, 2,099.76 and 989.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.62 : 2,099.76 = 989.55 : x
2. Step 2: Convert to fraction form
   1,399.62/2,099.76 = 989.55/x
3. Step 3: Cross multiply
   1,399.62x = 2,099.76 × 989.55
4. Step 4: Simplify right side
   1,399.62x = 2,077,817.51
5. Step 5: Solve for x
   x = 2,077,817.51/1,399.62
6. Step 6: Final answer
   x = 1,484.56