Finding the Third Proportional to 78.75 and 172.69

Step by Step Solution

1. Step 1: Write the proportion equation
   78.75 : 172.69 = 172.69 : x
2. Step 2: Convert to fraction form
   78.75/172.69 = 172.69/x
3. Step 3: Cross multiply
   78.75x = 172.69 × 172.69
4. Step 4: Simplify right side
   78.75x = 29,820.97
5. Step 5: Solve for x
   x = 29,820.97/78.75
6. Step 6: Final answer
   x = 378.68