Finding the Fourth Proportional to 1,317.90, 1,818.72 and 820.74

Step by Step Solution

1. Step 1: Write the proportion equation
   1,317.90 : 1,818.72 = 820.74 : x
2. Step 2: Convert to fraction form
   1,317.90/1,818.72 = 820.74/x
3. Step 3: Cross multiply
   1,317.90x = 1,818.72 × 820.74
4. Step 4: Simplify right side
   1,317.90x = 1,492,696.25
5. Step 5: Solve for x
   x = 1,492,696.25/1,317.90
6. Step 6: Final answer
   x = 1,132.63