Finding the Fourth Proportional to 1,087.40, 1,500.61 and 645.29

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.40 : 1,500.61 = 645.29 : x
2. Step 2: Convert to fraction form
   1,087.40/1,500.61 = 645.29/x
3. Step 3: Cross multiply
   1,087.40x = 1,500.61 × 645.29
4. Step 4: Simplify right side
   1,087.40x = 968,321.12
5. Step 5: Solve for x
   x = 968,321.12/1,087.40
6. Step 6: Final answer
   x = 890.50