Finding the Fourth Proportional to 1,173.71, 1,619.71 and 642.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,173.71 : 1,619.71 = 642.59 : x
2. Step 2: Convert to fraction form
   1,173.71/1,619.71 = 642.59/x
3. Step 3: Cross multiply
   1,173.71x = 1,619.71 × 642.59
4. Step 4: Simplify right side
   1,173.71x = 1,040,809.45
5. Step 5: Solve for x
   x = 1,040,809.45/1,173.71
6. Step 6: Final answer
   x = 886.77