Finding the Fourth Proportional to 91.69, 137.42 and 71.31

Step by Step Solution

1. Step 1: Write the proportion equation
   91.69 : 137.42 = 71.31 : x
2. Step 2: Convert to fraction form
   91.69/137.42 = 71.31/x
3. Step 3: Cross multiply
   91.69x = 137.42 × 71.31
4. Step 4: Simplify right side
   91.69x = 9,799.42
5. Step 5: Solve for x
   x = 9,799.42/91.69
6. Step 6: Final answer
   x = 106.88