Finding the Fourth Proportional to 1,087.74, 1,501.49 and 645.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.74 : 1,501.49 = 645.86 : x
2. Step 2: Convert to fraction form
   1,087.74/1,501.49 = 645.86/x
3. Step 3: Cross multiply
   1,087.74x = 1,501.49 × 645.86
4. Step 4: Simplify right side
   1,087.74x = 969,752.33
5. Step 5: Solve for x
   x = 969,752.33/1,087.74
6. Step 6: Final answer
   x = 891.53