Finding the Third Proportional to 42.50 and 90

Step by Step Solution

1. Step 1: Write the proportion equation
   42.50 : 90 = 90 : x
2. Step 2: Convert to fraction form
   42.50/90 = 90/x
3. Step 3: Cross multiply
   42.50x = 90 × 90
4. Step 4: Simplify right side
   42.50x = 8,100
5. Step 5: Solve for x
   x = 8,100/42.50
6. Step 6: Final answer
   x = 190.59