Finding the Fourth Proportional to 93.10, 128.42 and 72.43

Step by Step Solution

1. Step 1: Write the proportion equation
   93.10 : 128.42 = 72.43 : x
2. Step 2: Convert to fraction form
   93.10/128.42 = 72.43/x
3. Step 3: Cross multiply
   93.10x = 128.42 × 72.43
4. Step 4: Simplify right side
   93.10x = 9,301.46
5. Step 5: Solve for x
   x = 9,301.46/93.10
6. Step 6: Final answer
   x = 99.91