Finding the Fourth Proportional to 1,307.80, 1,962.24 and 820.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,307.80 : 1,962.24 = 820.72 : x
2. Step 2: Convert to fraction form
   1,307.80/1,962.24 = 820.72/x
3. Step 3: Cross multiply
   1,307.80x = 1,962.24 × 820.72
4. Step 4: Simplify right side
   1,307.80x = 1,610,449.61
5. Step 5: Solve for x
   x = 1,610,449.61/1,307.80
6. Step 6: Final answer
   x = 1,231.42