Finding the Fourth Proportional to 1,016.49, 1,402.72 and 643.35

Step by Step Solution

1. Step 1: Write the proportion equation
   1,016.49 : 1,402.72 = 643.35 : x
2. Step 2: Convert to fraction form
   1,016.49/1,402.72 = 643.35/x
3. Step 3: Cross multiply
   1,016.49x = 1,402.72 × 643.35
4. Step 4: Simplify right side
   1,016.49x = 902,439.91
5. Step 5: Solve for x
   x = 902,439.91/1,016.49
6. Step 6: Final answer
   x = 887.80