Finding the Fourth Proportional to 1,636.34, 2,260.71 and 1,390.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,636.34 : 2,260.71 = 1,390.23 : x
2. Step 2: Convert to fraction form
   1,636.34/2,260.71 = 1,390.23/x
3. Step 3: Cross multiply
   1,636.34x = 2,260.71 × 1,390.23
4. Step 4: Simplify right side
   1,636.34x = 3,142,906.86
5. Step 5: Solve for x
   x = 3,142,906.86/1,636.34
6. Step 6: Final answer
   x = 1,920.70