Finding the Fourth Proportional to 1,005.81, 1,388.41 and 900.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.81 : 1,388.41 = 900.72 : x
2. Step 2: Convert to fraction form
   1,005.81/1,388.41 = 900.72/x
3. Step 3: Cross multiply
   1,005.81x = 1,388.41 × 900.72
4. Step 4: Simplify right side
   1,005.81x = 1,250,568.66
5. Step 5: Solve for x
   x = 1,250,568.66/1,005.81
6. Step 6: Final answer
   x = 1,243.34