Finding the Fourth Proportional to 1,219.81, 1,681.59 and 869.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,219.81 : 1,681.59 = 869.89 : x
2. Step 2: Convert to fraction form
   1,219.81/1,681.59 = 869.89/x
3. Step 3: Cross multiply
   1,219.81x = 1,681.59 × 869.89
4. Step 4: Simplify right side
   1,219.81x = 1,462,793.98
5. Step 5: Solve for x
   x = 1,462,793.98/1,219.81
6. Step 6: Final answer
   x = 1,199.20