Finding the Fourth Proportional to 109.21, 150.72 and 71.89

Step by Step Solution

1. Step 1: Write the proportion equation
   109.21 : 150.72 = 71.89 : x
2. Step 2: Convert to fraction form
   109.21/150.72 = 71.89/x
3. Step 3: Cross multiply
   109.21x = 150.72 × 71.89
4. Step 4: Simplify right side
   109.21x = 10,835.26
5. Step 5: Solve for x
   x = 10,835.26/109.21
6. Step 6: Final answer
   x = 99.21