Finding the Fourth Proportional to 1,321.48, 1,980.79 and 859.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,321.48 : 1,980.79 = 859.59 : x
2. Step 2: Convert to fraction form
   1,321.48/1,980.79 = 859.59/x
3. Step 3: Cross multiply
   1,321.48x = 1,980.79 × 859.59
4. Step 4: Simplify right side
   1,321.48x = 1,702,667.28
5. Step 5: Solve for x
   x = 1,702,667.28/1,321.48
6. Step 6: Final answer
   x = 1,288.45