Finding the Fourth Proportional to 1,087.65, 1,499.60 and 645.39

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.65 : 1,499.60 = 645.39 : x
2. Step 2: Convert to fraction form
   1,087.65/1,499.60 = 645.39/x
3. Step 3: Cross multiply
   1,087.65x = 1,499.60 × 645.39
4. Step 4: Simplify right side
   1,087.65x = 967,823.62
5. Step 5: Solve for x
   x = 967,823.62/1,087.65
6. Step 6: Final answer
   x = 889.83