Finding the Fourth Proportional to 1,603.89, 2,213.06 and 905.13

Step by Step Solution

1. Step 1: Write the proportion equation
   1,603.89 : 2,213.06 = 905.13 : x
2. Step 2: Convert to fraction form
   1,603.89/2,213.06 = 905.13/x
3. Step 3: Cross multiply
   1,603.89x = 2,213.06 × 905.13
4. Step 4: Simplify right side
   1,603.89x = 2,003,102.47
5. Step 5: Solve for x
   x = 2,003,102.47/1,603.89
6. Step 6: Final answer
   x = 1,248.90