Finding the Fourth Proportional to 28.78, 42.83 and 28.02

Step by Step Solution

1. Step 1: Write the proportion equation
   28.78 : 42.83 = 28.02 : x
2. Step 2: Convert to fraction form
   28.78/42.83 = 28.02/x
3. Step 3: Cross multiply
   28.78x = 42.83 × 28.02
4. Step 4: Simplify right side
   28.78x = 1,200.10
5. Step 5: Solve for x
   x = 1,200.10/28.78
6. Step 6: Final answer
   x = 41.70