Finding the Fourth Proportional to 105.39, 145.35 and 72.63

Step by Step Solution

1. Step 1: Write the proportion equation
   105.39 : 145.35 = 72.63 : x
2. Step 2: Convert to fraction form
   105.39/145.35 = 72.63/x
3. Step 3: Cross multiply
   105.39x = 145.35 × 72.63
4. Step 4: Simplify right side
   105.39x = 10,556.77
5. Step 5: Solve for x
   x = 10,556.77/105.39
6. Step 6: Final answer
   x = 100.17