Finding the Fourth Proportional to 105.42, 145.32 and 72.74

Step by Step Solution

1. Step 1: Write the proportion equation
   105.42 : 145.32 = 72.74 : x
2. Step 2: Convert to fraction form
   105.42/145.32 = 72.74/x
3. Step 3: Cross multiply
   105.42x = 145.32 × 72.74
4. Step 4: Simplify right side
   105.42x = 10,570.58
5. Step 5: Solve for x
   x = 10,570.58/105.42
6. Step 6: Final answer
   x = 100.27