Finding the Fourth Proportional to 744.72, 1,116.86 and 639.59

Step by Step Solution

1. Step 1: Write the proportion equation
   744.72 : 1,116.86 = 639.59 : x
2. Step 2: Convert to fraction form
   744.72/1,116.86 = 639.59/x
3. Step 3: Cross multiply
   744.72x = 1,116.86 × 639.59
4. Step 4: Simplify right side
   744.72x = 714,323.71
5. Step 5: Solve for x
   x = 714,323.71/744.72
6. Step 6: Final answer
   x = 959.18