Finding the Fourth Proportional to 1,870.72, 2,806.38 and 638.00

Step by Step Solution

1. Step 1: Write the proportion equation
   1,870.72 : 2,806.38 = 638.00 : x
2. Step 2: Convert to fraction form
   1,870.72/2,806.38 = 638.00/x
3. Step 3: Cross multiply
   1,870.72x = 2,806.38 × 638.00
4. Step 4: Simplify right side
   1,870.72x = 1,790,477.46
5. Step 5: Solve for x
   x = 1,790,477.46/1,870.72
6. Step 6: Final answer
   x = 957.11