Finding the Fourth Proportional to 2,122.56, 2,928.72 and 1,238.40

Step by Step Solution

1. Step 1: Write the proportion equation
   2,122.56 : 2,928.72 = 1,238.40 : x
2. Step 2: Convert to fraction form
   2,122.56/2,928.72 = 1,238.40/x
3. Step 3: Cross multiply
   2,122.56x = 2,928.72 × 1,238.40
4. Step 4: Simplify right side
   2,122.56x = 3,626,926.85
5. Step 5: Solve for x
   x = 3,626,926.85/2,122.56
6. Step 6: Final answer
   x = 1,708.75