Finding the Fourth Proportional to 1,688.72, 2,329.32 and 989.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,688.72 : 2,329.32 = 989.60 : x
2. Step 2: Convert to fraction form
   1,688.72/2,329.32 = 989.60/x
3. Step 3: Cross multiply
   1,688.72x = 2,329.32 × 989.60
4. Step 4: Simplify right side
   1,688.72x = 2,305,095.07
5. Step 5: Solve for x
   x = 2,305,095.07/1,688.72
6. Step 6: Final answer
   x = 1,365.00