Finding the Fourth Proportional to 1,284.24, 1,922.72 and 820.87

Step by Step Solution

1. Step 1: Write the proportion equation
   1,284.24 : 1,922.72 = 820.87 : x
2. Step 2: Convert to fraction form
   1,284.24/1,922.72 = 820.87/x
3. Step 3: Cross multiply
   1,284.24x = 1,922.72 × 820.87
4. Step 4: Simplify right side
   1,284.24x = 1,578,303.17
5. Step 5: Solve for x
   x = 1,578,303.17/1,284.24
6. Step 6: Final answer
   x = 1,228.98