Finding the Fourth Proportional to 1,071.42, 1,606.32 and 638.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,071.42 : 1,606.32 = 638.88 : x
2. Step 2: Convert to fraction form
   1,071.42/1,606.32 = 638.88/x
3. Step 3: Cross multiply
   1,071.42x = 1,606.32 × 638.88
4. Step 4: Simplify right side
   1,071.42x = 1,026,245.72
5. Step 5: Solve for x
   x = 1,026,245.72/1,071.42
6. Step 6: Final answer
   x = 957.84