Finding the Fourth Proportional to 1,165.76, 1,608.72 and 641.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,165.76 : 1,608.72 = 641.76 : x
2. Step 2: Convert to fraction form
   1,165.76/1,608.72 = 641.76/x
3. Step 3: Cross multiply
   1,165.76x = 1,608.72 × 641.76
4. Step 4: Simplify right side
   1,165.76x = 1,032,412.15
5. Step 5: Solve for x
   x = 1,032,412.15/1,165.76
6. Step 6: Final answer
   x = 885.61