Finding the Third Proportional to 21.56 and 53.91

Step by Step Solution

1. Step 1: Write the proportion equation
   21.56 : 53.91 = 53.91 : x
2. Step 2: Convert to fraction form
   21.56/53.91 = 53.91/x
3. Step 3: Cross multiply
   21.56x = 53.91 × 53.91
4. Step 4: Simplify right side
   21.56x = 2,905.88
5. Step 5: Solve for x
   x = 2,905.88/21.56
6. Step 6: Final answer
   x = 134.77