Finding the Fourth Proportional to 1,317.21, 1,816.71 and 845.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,317.21 : 1,816.71 = 845.15 : x
2. Step 2: Convert to fraction form
   1,317.21/1,816.71 = 845.15/x
3. Step 3: Cross multiply
   1,317.21x = 1,816.71 × 845.15
4. Step 4: Simplify right side
   1,317.21x = 1,535,383.37
5. Step 5: Solve for x
   x = 1,535,383.37/1,317.21
6. Step 6: Final answer
   x = 1,165.63