Finding the Fourth Proportional to 1,140.06, 1,573.35 and 642.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,140.06 : 1,573.35 = 642.72 : x
2. Step 2: Convert to fraction form
   1,140.06/1,573.35 = 642.72/x
3. Step 3: Cross multiply
   1,140.06x = 1,573.35 × 642.72
4. Step 4: Simplify right side
   1,140.06x = 1,011,223.51
5. Step 5: Solve for x
   x = 1,011,223.51/1,140.06
6. Step 6: Final answer
   x = 886.99