Finding the Fourth Proportional to 1,106.21, 1,658.79 and 644.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,106.21 : 1,658.79 = 644.10 : x
2. Step 2: Convert to fraction form
   1,106.21/1,658.79 = 644.10/x
3. Step 3: Cross multiply
   1,106.21x = 1,658.79 × 644.10
4. Step 4: Simplify right side
   1,106.21x = 1,068,426.64
5. Step 5: Solve for x
   x = 1,068,426.64/1,106.21
6. Step 6: Final answer
   x = 965.84