Finding the Fourth Proportional to 1,016.75, 1,403.12 and 643.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,016.75 : 1,403.12 = 643.34 : x
2. Step 2: Convert to fraction form
   1,016.75/1,403.12 = 643.34/x
3. Step 3: Cross multiply
   1,016.75x = 1,403.12 × 643.34
4. Step 4: Simplify right side
   1,016.75x = 902,688.34
5. Step 5: Solve for x
   x = 902,688.34/1,016.75
6. Step 6: Final answer
   x = 887.82