Finding the Third Proportional to 21.42 and 42.28

Step by Step Solution

1. Step 1: Write the proportion equation
   21.42 : 42.28 = 42.28 : x
2. Step 2: Convert to fraction form
   21.42/42.28 = 42.28/x
3. Step 3: Cross multiply
   21.42x = 42.28 × 42.28
4. Step 4: Simplify right side
   21.42x = 1,787.70
5. Step 5: Solve for x
   x = 1,787.70/21.42
6. Step 6: Final answer
   x = 83.45