Finding the Fourth Proportional to 2,017.80, 2,784.64 and 1,221.38

Step by Step Solution

1. Step 1: Write the proportion equation
   2,017.80 : 2,784.64 = 1,221.38 : x
2. Step 2: Convert to fraction form
   2,017.80/2,784.64 = 1,221.38/x
3. Step 3: Cross multiply
   2,017.80x = 2,784.64 × 1,221.38
4. Step 4: Simplify right side
   2,017.80x = 3,401,103.60
5. Step 5: Solve for x
   x = 3,401,103.60/2,017.80
6. Step 6: Final answer
   x = 1,685.55