Finding the Fourth Proportional to 1,870.68, 2,805.86 and 638.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,870.68 : 2,805.86 = 638.12 : x
2. Step 2: Convert to fraction form
   1,870.68/2,805.86 = 638.12/x
3. Step 3: Cross multiply
   1,870.68x = 2,805.86 × 638.12
4. Step 4: Simplify right side
   1,870.68x = 1,790,475.38
5. Step 5: Solve for x
   x = 1,790,475.38/1,870.68
6. Step 6: Final answer
   x = 957.13