Finding the Fourth Proportional to 3,714.79, 5,128.74 and 2,390.80

Step by Step Solution

1. Step 1: Write the proportion equation
   3,714.79 : 5,128.74 = 2,390.80 : x
2. Step 2: Convert to fraction form
   3,714.79/5,128.74 = 2,390.80/x
3. Step 3: Cross multiply
   3,714.79x = 5,128.74 × 2,390.80
4. Step 4: Simplify right side
   3,714.79x = 12,261,791.59
5. Step 5: Solve for x
   x = 12,261,791.59/3,714.79
6. Step 6: Final answer
   x = 3,300.80