Finding the Fourth Proportional to 1,007.67, 1,513.91 and 643.17

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.67 : 1,513.91 = 643.17 : x
2. Step 2: Convert to fraction form
   1,007.67/1,513.91 = 643.17/x
3. Step 3: Cross multiply
   1,007.67x = 1,513.91 × 643.17
4. Step 4: Simplify right side
   1,007.67x = 973,698.28
5. Step 5: Solve for x
   x = 973,698.28/1,007.67
6. Step 6: Final answer
   x = 966.29