Finding the Fourth Proportional to 105.78, 145.98 and 62.12

Step by Step Solution

1. Step 1: Write the proportion equation
   105.78 : 145.98 = 62.12 : x
2. Step 2: Convert to fraction form
   105.78/145.98 = 62.12/x
3. Step 3: Cross multiply
   105.78x = 145.98 × 62.12
4. Step 4: Simplify right side
   105.78x = 9,068.28
5. Step 5: Solve for x
   x = 9,068.28/105.78
6. Step 6: Final answer
   x = 85.73