Finding the Fourth Proportional to 100.71, 139.01 and 89.06

Step by Step Solution

1. Step 1: Write the proportion equation
   100.71 : 139.01 = 89.06 : x
2. Step 2: Convert to fraction form
   100.71/139.01 = 89.06/x
3. Step 3: Cross multiply
   100.71x = 139.01 × 89.06
4. Step 4: Simplify right side
   100.71x = 12,379.09
5. Step 5: Solve for x
   x = 12,379.09/100.71
6. Step 6: Final answer
   x = 122.92