Finding the Fourth Proportional to 1,259.34, 1,890.18 and 643.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,259.34 : 1,890.18 = 643.48 : x
2. Step 2: Convert to fraction form
   1,259.34/1,890.18 = 643.48/x
3. Step 3: Cross multiply
   1,259.34x = 1,890.18 × 643.48
4. Step 4: Simplify right side
   1,259.34x = 1,216,298.93
5. Step 5: Solve for x
   x = 1,216,298.93/1,259.34
6. Step 6: Final answer
   x = 965.83