Finding the Fourth Proportional to 42.75, 64.15 and 42.40

Step by Step Solution

1. Step 1: Write the proportion equation
   42.75 : 64.15 = 42.40 : x
2. Step 2: Convert to fraction form
   42.75/64.15 = 42.40/x
3. Step 3: Cross multiply
   42.75x = 64.15 × 42.40
4. Step 4: Simplify right side
   42.75x = 2,719.96
5. Step 5: Solve for x
   x = 2,719.96/42.75
6. Step 6: Final answer
   x = 63.62