Finding the Fourth Proportional to 1,572.21, 2,169.69 and 864.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,572.21 : 2,169.69 = 864.09 : x
2. Step 2: Convert to fraction form
   1,572.21/2,169.69 = 864.09/x
3. Step 3: Cross multiply
   1,572.21x = 2,169.69 × 864.09
4. Step 4: Simplify right side
   1,572.21x = 1,874,807.43
5. Step 5: Solve for x
   x = 1,874,807.43/1,572.21
6. Step 6: Final answer
   x = 1,192.47