Finding the Fourth Proportional to 1,120.71, 1,547.12 and 789.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,120.71 : 1,547.12 = 789.42 : x
2. Step 2: Convert to fraction form
   1,120.71/1,547.12 = 789.42/x
3. Step 3: Cross multiply
   1,120.71x = 1,547.12 × 789.42
4. Step 4: Simplify right side
   1,120.71x = 1,221,327.47
5. Step 5: Solve for x
   x = 1,221,327.47/1,120.71
6. Step 6: Final answer
   x = 1,089.78