Finding the Fourth Proportional to 2,209.80, 3,315.86 and 978.06

Step by Step Solution

1. Step 1: Write the proportion equation
   2,209.80 : 3,315.86 = 978.06 : x
2. Step 2: Convert to fraction form
   2,209.80/3,315.86 = 978.06/x
3. Step 3: Cross multiply
   2,209.80x = 3,315.86 × 978.06
4. Step 4: Simplify right side
   2,209.80x = 3,243,110.03
5. Step 5: Solve for x
   x = 3,243,110.03/2,209.80
6. Step 6: Final answer
   x = 1,467.60