Finding the Fourth Proportional to 1,998.69, 2,757.78 and 1,212.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,998.69 : 2,757.78 = 1,212.30 : x
2. Step 2: Convert to fraction form
   1,998.69/2,757.78 = 1,212.30/x
3. Step 3: Cross multiply
   1,998.69x = 2,757.78 × 1,212.30
4. Step 4: Simplify right side
   1,998.69x = 3,343,256.69
5. Step 5: Solve for x
   x = 3,343,256.69/1,998.69
6. Step 6: Final answer
   x = 1,672.72