Finding the Fourth Proportional to 1,016.32, 1,401.88 and 642.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,016.32 : 1,401.88 = 642.64 : x
2. Step 2: Convert to fraction form
   1,016.32/1,401.88 = 642.64/x
3. Step 3: Cross multiply
   1,016.32x = 1,401.88 × 642.64
4. Step 4: Simplify right side
   1,016.32x = 900,904.16
5. Step 5: Solve for x
   x = 900,904.16/1,016.32
6. Step 6: Final answer
   x = 886.44