Finding the Fourth Proportional to 2,621.84, 3,929.82 and 1,320.57

Step by Step Solution

1. Step 1: Write the proportion equation
   2,621.84 : 3,929.82 = 1,320.57 : x
2. Step 2: Convert to fraction form
   2,621.84/3,929.82 = 1,320.57/x
3. Step 3: Cross multiply
   2,621.84x = 3,929.82 × 1,320.57
4. Step 4: Simplify right side
   2,621.84x = 5,189,597.45
5. Step 5: Solve for x
   x = 5,189,597.45/2,621.84
6. Step 6: Final answer
   x = 1,979.38