Finding the Fourth Proportional to 1,087.83, 1,501.20 and 645.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.83 : 1,501.20 = 645.77 : x
2. Step 2: Convert to fraction form
   1,087.83/1,501.20 = 645.77/x
3. Step 3: Cross multiply
   1,087.83x = 1,501.20 × 645.77
4. Step 4: Simplify right side
   1,087.83x = 969,422.42
5. Step 5: Solve for x
   x = 969,422.42/1,087.83
6. Step 6: Final answer
   x = 891.15