Finding the Fourth Proportional to 820.55, 1,133.25 and 715.15

Step by Step Solution

1. Step 1: Write the proportion equation
   820.55 : 1,133.25 = 715.15 : x
2. Step 2: Convert to fraction form
   820.55/1,133.25 = 715.15/x
3. Step 3: Cross multiply
   820.55x = 1,133.25 × 715.15
4. Step 4: Simplify right side
   820.55x = 810,443.74
5. Step 5: Solve for x
   x = 810,443.74/820.55
6. Step 6: Final answer
   x = 987.68