Finding the Fourth Proportional to 2,591.31, 3,886.96 and 643.52

Step by Step Solution

1. Step 1: Write the proportion equation
   2,591.31 : 3,886.96 = 643.52 : x
2. Step 2: Convert to fraction form
   2,591.31/3,886.96 = 643.52/x
3. Step 3: Cross multiply
   2,591.31x = 3,886.96 × 643.52
4. Step 4: Simplify right side
   2,591.31x = 2,501,325.17
5. Step 5: Solve for x
   x = 2,501,325.17/2,591.31
6. Step 6: Final answer
   x = 965.27