Finding the Fourth Proportional to 123.59, 170.71 and 100.31

Step by Step Solution

1. Step 1: Write the proportion equation
   123.59 : 170.71 = 100.31 : x
2. Step 2: Convert to fraction form
   123.59/170.71 = 100.31/x
3. Step 3: Cross multiply
   123.59x = 170.71 × 100.31
4. Step 4: Simplify right side
   123.59x = 17,122.82
5. Step 5: Solve for x
   x = 17,122.82/123.59
6. Step 6: Final answer
   x = 138.54