Finding the Fourth Proportional to 820.69, 1,222.56 and 770.27

Step by Step Solution

1. Step 1: Write the proportion equation
   820.69 : 1,222.56 = 770.27 : x
2. Step 2: Convert to fraction form
   820.69/1,222.56 = 770.27/x
3. Step 3: Cross multiply
   820.69x = 1,222.56 × 770.27
4. Step 4: Simplify right side
   820.69x = 941,699.76
5. Step 5: Solve for x
   x = 941,699.76/820.69
6. Step 6: Final answer
   x = 1,147.45