Finding the Fourth Proportional to 1,688.65, 2,528.52 and 1,321.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,688.65 : 2,528.52 = 1,321.72 : x
2. Step 2: Convert to fraction form
   1,688.65/2,528.52 = 1,321.72/x
3. Step 3: Cross multiply
   1,688.65x = 2,528.52 × 1,321.72
4. Step 4: Simplify right side
   1,688.65x = 3,341,995.45
5. Step 5: Solve for x
   x = 3,341,995.45/1,688.65
6. Step 6: Final answer
   x = 1,979.09