Finding the Fourth Proportional to 99.50, 149.31 and 42.50

Step by Step Solution

1. Step 1: Write the proportion equation
   99.50 : 149.31 = 42.50 : x
2. Step 2: Convert to fraction form
   99.50/149.31 = 42.50/x
3. Step 3: Cross multiply
   99.50x = 149.31 × 42.50
4. Step 4: Simplify right side
   99.50x = 6,345.68
5. Step 5: Solve for x
   x = 6,345.68/99.50
6. Step 6: Final answer
   x = 63.78