Finding the Fourth Proportional to 1,087.76, 1,500.54 and 645.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.76 : 1,500.54 = 645.81 : x
2. Step 2: Convert to fraction form
   1,087.76/1,500.54 = 645.81/x
3. Step 3: Cross multiply
   1,087.76x = 1,500.54 × 645.81
4. Step 4: Simplify right side
   1,087.76x = 969,063.74
5. Step 5: Solve for x
   x = 969,063.74/1,087.76
6. Step 6: Final answer
   x = 890.88