Finding the Fourth Proportional to 2,145.18, 3,218.16 and 1,221.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,145.18 : 3,218.16 = 1,221.78 : x
2. Step 2: Convert to fraction form
   2,145.18/3,218.16 = 1,221.78/x
3. Step 3: Cross multiply
   2,145.18x = 3,218.16 × 1,221.78
4. Step 4: Simplify right side
   2,145.18x = 3,931,883.52
5. Step 5: Solve for x
   x = 3,931,883.52/2,145.18
6. Step 6: Final answer
   x = 1,832.89