Finding the Fourth Proportional to 1,389.81, 1,917.32 and 917.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.81 : 1,917.32 = 917.10 : x
2. Step 2: Convert to fraction form
   1,389.81/1,917.32 = 917.10/x
3. Step 3: Cross multiply
   1,389.81x = 1,917.32 × 917.10
4. Step 4: Simplify right side
   1,389.81x = 1,758,369.59
5. Step 5: Solve for x
   x = 1,758,369.59/1,389.81
6. Step 6: Final answer
   x = 1,265.19