Finding the Fourth Proportional to 2,212.20, 3,315.60 and 978.30

Step by Step Solution

1. Step 1: Write the proportion equation
   2,212.20 : 3,315.60 = 978.30 : x
2. Step 2: Convert to fraction form
   2,212.20/3,315.60 = 978.30/x
3. Step 3: Cross multiply
   2,212.20x = 3,315.60 × 978.30
4. Step 4: Simplify right side
   2,212.20x = 3,243,651.48
5. Step 5: Solve for x
   x = 3,243,651.48/2,212.20
6. Step 6: Final answer
   x = 1,466.26