Finding the Fourth Proportional to 2,171.78, 3,256.88 and 784.79

Step by Step Solution

1. Step 1: Write the proportion equation
   2,171.78 : 3,256.88 = 784.79 : x
2. Step 2: Convert to fraction form
   2,171.78/3,256.88 = 784.79/x
3. Step 3: Cross multiply
   2,171.78x = 3,256.88 × 784.79
4. Step 4: Simplify right side
   2,171.78x = 2,555,946.65
5. Step 5: Solve for x
   x = 2,555,946.65/2,171.78
6. Step 6: Final answer
   x = 1,176.89