Finding the Fourth Proportional to 1,087.42, 1,500.90 and 645.58

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.42 : 1,500.90 = 645.58 : x
2. Step 2: Convert to fraction form
   1,087.42/1,500.90 = 645.58/x
3. Step 3: Cross multiply
   1,087.42x = 1,500.90 × 645.58
4. Step 4: Simplify right side
   1,087.42x = 968,942.03
5. Step 5: Solve for x
   x = 968,942.03/1,087.42
6. Step 6: Final answer
   x = 891.05