Finding the Fourth Proportional to 1,085.42, 1,498.17 and 643.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.42 : 1,498.17 = 643.64 : x
2. Step 2: Convert to fraction form
   1,085.42/1,498.17 = 643.64/x
3. Step 3: Cross multiply
   1,085.42x = 1,498.17 × 643.64
4. Step 4: Simplify right side
   1,085.42x = 964,282.14
5. Step 5: Solve for x
   x = 964,282.14/1,085.42
6. Step 6: Final answer
   x = 888.40