Finding the Fourth Proportional to 1,291.69, 1,936.52 and 642.07

Step by Step Solution

1. Step 1: Write the proportion equation
   1,291.69 : 1,936.52 = 642.07 : x
2. Step 2: Convert to fraction form
   1,291.69/1,936.52 = 642.07/x
3. Step 3: Cross multiply
   1,291.69x = 1,936.52 × 642.07
4. Step 4: Simplify right side
   1,291.69x = 1,243,381.40
5. Step 5: Solve for x
   x = 1,243,381.40/1,291.69
6. Step 6: Final answer
   x = 962.60