Finding the Fourth Proportional to 42.50, 63.77 and 28.05

Step by Step Solution

1. Step 1: Write the proportion equation
   42.50 : 63.77 = 28.05 : x
2. Step 2: Convert to fraction form
   42.50/63.77 = 28.05/x
3. Step 3: Cross multiply
   42.50x = 63.77 × 28.05
4. Step 4: Simplify right side
   42.50x = 1,788.82
5. Step 5: Solve for x
   x = 1,788.82/42.50
6. Step 6: Final answer
   x = 42.09