Finding the Fourth Proportional to 1,928.72, 2,662.44 and 1,290.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,928.72 : 2,662.44 = 1,290.80 : x
2. Step 2: Convert to fraction form
   1,928.72/2,662.44 = 1,290.80/x
3. Step 3: Cross multiply
   1,928.72x = 2,662.44 × 1,290.80
4. Step 4: Simplify right side
   1,928.72x = 3,436,677.55
5. Step 5: Solve for x
   x = 3,436,677.55/1,928.72
6. Step 6: Final answer
   x = 1,781.84