Finding the Fourth Proportional to 1,016.45, 1,402.56 and 642.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,016.45 : 1,402.56 = 642.77 : x
2. Step 2: Convert to fraction form
   1,016.45/1,402.56 = 642.77/x
3. Step 3: Cross multiply
   1,016.45x = 1,402.56 × 642.77
4. Step 4: Simplify right side
   1,016.45x = 901,516.48
5. Step 5: Solve for x
   x = 901,516.48/1,016.45
6. Step 6: Final answer
   x = 886.93