Finding the Fourth Proportional to 1,109.69, 1,531.38 and 644.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,109.69 : 1,531.38 = 644.21 : x
2. Step 2: Convert to fraction form
   1,109.69/1,531.38 = 644.21/x
3. Step 3: Cross multiply
   1,109.69x = 1,531.38 × 644.21
4. Step 4: Simplify right side
   1,109.69x = 986,530.31
5. Step 5: Solve for x
   x = 986,530.31/1,109.69
6. Step 6: Final answer
   x = 889.01