Finding the Fourth Proportional to 1,018.25, 1,405.24 and 645.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,018.25 : 1,405.24 = 645.10 : x
2. Step 2: Convert to fraction form
   1,018.25/1,405.24 = 645.10/x
3. Step 3: Cross multiply
   1,018.25x = 1,405.24 × 645.10
4. Step 4: Simplify right side
   1,018.25x = 906,520.32
5. Step 5: Solve for x
   x = 906,520.32/1,018.25
6. Step 6: Final answer
   x = 890.27