Finding the Fourth Proportional to 1,042.65, 1,438.72 and 623.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,042.65 : 1,438.72 = 623.05 : x
2. Step 2: Convert to fraction form
   1,042.65/1,438.72 = 623.05/x
3. Step 3: Cross multiply
   1,042.65x = 1,438.72 × 623.05
4. Step 4: Simplify right side
   1,042.65x = 896,389.34
5. Step 5: Solve for x
   x = 896,389.34/1,042.65
6. Step 6: Final answer
   x = 859.72