Finding the Fourth Proportional to 1,389.24, 2,080.80 and 900.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.24 : 2,080.80 = 900.81 : x
2. Step 2: Convert to fraction form
   1,389.24/2,080.80 = 900.81/x
3. Step 3: Cross multiply
   1,389.24x = 2,080.80 × 900.81
4. Step 4: Simplify right side
   1,389.24x = 1,874,405.45
5. Step 5: Solve for x
   x = 1,874,405.45/1,389.24
6. Step 6: Final answer
   x = 1,349.23