Finding the Fourth Proportional to 1,085.09, 1,496.95 and 642.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.09 : 1,496.95 = 642.74 : x
2. Step 2: Convert to fraction form
   1,085.09/1,496.95 = 642.74/x
3. Step 3: Cross multiply
   1,085.09x = 1,496.95 × 642.74
4. Step 4: Simplify right side
   1,085.09x = 962,151.78
5. Step 5: Solve for x
   x = 962,151.78/1,085.09
6. Step 6: Final answer
   x = 886.70