Finding the Fourth Proportional to 1,189.56, 1,642.86 and 817.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189.56 : 1,642.86 = 817.50 : x
2. Step 2: Convert to fraction form
   1,189.56/1,642.86 = 817.50/x
3. Step 3: Cross multiply
   1,189.56x = 1,642.86 × 817.50
4. Step 4: Simplify right side
   1,189.56x = 1,343,038.05
5. Step 5: Solve for x
   x = 1,343,038.05/1,189.56
6. Step 6: Final answer
   x = 1,129.02