Finding the Fourth Proportional to 89.69, 123.71 and 79.31

Step by Step Solution

1. Step 1: Write the proportion equation
   89.69 : 123.71 = 79.31 : x
2. Step 2: Convert to fraction form
   89.69/123.71 = 79.31/x
3. Step 3: Cross multiply
   89.69x = 123.71 × 79.31
4. Step 4: Simplify right side
   89.69x = 9,811.35
5. Step 5: Solve for x
   x = 9,811.35/89.69
6. Step 6: Final answer
   x = 109.40