Finding the Fourth Proportional to 870.72, 1,192.56 and 820.23

Step by Step Solution

1. Step 1: Write the proportion equation
   870.72 : 1,192.56 = 820.23 : x
2. Step 2: Convert to fraction form
   870.72/1,192.56 = 820.23/x
3. Step 3: Cross multiply
   870.72x = 1,192.56 × 820.23
4. Step 4: Simplify right side
   870.72x = 978,173.49
5. Step 5: Solve for x
   x = 978,173.49/870.72
6. Step 6: Final answer
   x = 1,123.41