Finding the Fourth Proportional to 3,786.60, 5,678.52 and 1,320.72

Step by Step Solution

1. Step 1: Write the proportion equation
   3,786.60 : 5,678.52 = 1,320.72 : x
2. Step 2: Convert to fraction form
   3,786.60/5,678.52 = 1,320.72/x
3. Step 3: Cross multiply
   3,786.60x = 5,678.52 × 1,320.72
4. Step 4: Simplify right side
   3,786.60x = 7,499,734.93
5. Step 5: Solve for x
   x = 7,499,734.93/3,786.60
6. Step 6: Final answer
   x = 1,980.60