Finding the Fourth Proportional to 1,211.12, 1,670.24 and 818.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,211.12 : 1,670.24 = 818.72 : x
2. Step 2: Convert to fraction form
   1,211.12/1,670.24 = 818.72/x
3. Step 3: Cross multiply
   1,211.12x = 1,670.24 × 818.72
4. Step 4: Simplify right side
   1,211.12x = 1,367,458.89
5. Step 5: Solve for x
   x = 1,367,458.89/1,211.12
6. Step 6: Final answer
   x = 1,129.09