Finding the Fourth Proportional to 1,315.58, 1,969.72 and 664.95

Step by Step Solution

1. Step 1: Write the proportion equation
   1,315.58 : 1,969.72 = 664.95 : x
2. Step 2: Convert to fraction form
   1,315.58/1,969.72 = 664.95/x
3. Step 3: Cross multiply
   1,315.58x = 1,969.72 × 664.95
4. Step 4: Simplify right side
   1,315.58x = 1,309,763.65
5. Step 5: Solve for x
   x = 1,309,763.65/1,315.58
6. Step 6: Final answer
   x = 995.58