Finding the Fourth Proportional to 1,228.30, 1,839.28 and 816.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,228.30 : 1,839.28 = 816.15 : x
2. Step 2: Convert to fraction form
   1,228.30/1,839.28 = 816.15/x
3. Step 3: Cross multiply
   1,228.30x = 1,839.28 × 816.15
4. Step 4: Simplify right side
   1,228.30x = 1,501,128.37
5. Step 5: Solve for x
   x = 1,501,128.37/1,228.30
6. Step 6: Final answer
   x = 1,222.12