Finding the Fourth Proportional to 1,213.98, 1,818.36 and 1,128.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,213.98 : 1,818.36 = 1,128.48 : x
2. Step 2: Convert to fraction form
   1,213.98/1,818.36 = 1,128.48/x
3. Step 3: Cross multiply
   1,213.98x = 1,818.36 × 1,128.48
4. Step 4: Simplify right side
   1,213.98x = 2,051,982.89
5. Step 5: Solve for x
   x = 2,051,982.89/1,213.98
6. Step 6: Final answer
   x = 1,690.29