Finding the Fourth Proportional to 1,085.67, 1,498.23 and 643.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.67 : 1,498.23 = 643.77 : x
2. Step 2: Convert to fraction form
   1,085.67/1,498.23 = 643.77/x
3. Step 3: Cross multiply
   1,085.67x = 1,498.23 × 643.77
4. Step 4: Simplify right side
   1,085.67x = 964,515.53
5. Step 5: Solve for x
   x = 964,515.53/1,085.67
6. Step 6: Final answer
   x = 888.41