Finding the Fourth Proportional to 2,164.90, 2,987.52 and 1,220.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,164.90 : 2,987.52 = 1,220.78 : x
2. Step 2: Convert to fraction form
   2,164.90/2,987.52 = 1,220.78/x
3. Step 3: Cross multiply
   2,164.90x = 2,987.52 × 1,220.78
4. Step 4: Simplify right side
   2,164.90x = 3,647,104.67
5. Step 5: Solve for x
   x = 3,647,104.67/2,164.90
6. Step 6: Final answer
   x = 1,684.65