Finding the Fourth Proportional to 1,087.51, 1,500.72 and 645.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.51 : 1,500.72 = 645.15 : x
2. Step 2: Convert to fraction form
   1,087.51/1,500.72 = 645.15/x
3. Step 3: Cross multiply
   1,087.51x = 1,500.72 × 645.15
4. Step 4: Simplify right side
   1,087.51x = 968,189.51
5. Step 5: Solve for x
   x = 968,189.51/1,087.51
6. Step 6: Final answer
   x = 890.28