Finding the Fourth Proportional to 78.58, 117.89 and 42.50

Step by Step Solution

1. Step 1: Write the proportion equation
   78.58 : 117.89 = 42.50 : x
2. Step 2: Convert to fraction form
   78.58/117.89 = 42.50/x
3. Step 3: Cross multiply
   78.58x = 117.89 × 42.50
4. Step 4: Simplify right side
   78.58x = 5,010.33
5. Step 5: Solve for x
   x = 5,010.33/78.58
6. Step 6: Final answer
   x = 63.76