Finding the Fourth Proportional to 1,209.48, 1,667.28 and 815.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.48 : 1,667.28 = 815.88 : x
2. Step 2: Convert to fraction form
   1,209.48/1,667.28 = 815.88/x
3. Step 3: Cross multiply
   1,209.48x = 1,667.28 × 815.88
4. Step 4: Simplify right side
   1,209.48x = 1,360,300.41
5. Step 5: Solve for x
   x = 1,360,300.41/1,209.48
6. Step 6: Final answer
   x = 1,124.70