Finding the Fourth Proportional to 123.69, 170.72 and 78.84

Step by Step Solution

1. Step 1: Write the proportion equation
   123.69 : 170.72 = 78.84 : x
2. Step 2: Convert to fraction form
   123.69/170.72 = 78.84/x
3. Step 3: Cross multiply
   123.69x = 170.72 × 78.84
4. Step 4: Simplify right side
   123.69x = 13,460.19
5. Step 5: Solve for x
   x = 13,460.19/123.69
6. Step 6: Final answer
   x = 108.82