Finding the Fourth Proportional to 1,355.25, 1,870.26 and 890.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,355.25 : 1,870.26 = 890.31 : x
2. Step 2: Convert to fraction form
   1,355.25/1,870.26 = 890.31/x
3. Step 3: Cross multiply
   1,355.25x = 1,870.26 × 890.31
4. Step 4: Simplify right side
   1,355.25x = 1,665,111.18
5. Step 5: Solve for x
   x = 1,665,111.18/1,355.25
6. Step 6: Final answer
   x = 1,228.64