Finding the Fourth Proportional to 1,221.69, 1,685.93 and 662.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,221.69 : 1,685.93 = 662.15 : x
2. Step 2: Convert to fraction form
   1,221.69/1,685.93 = 662.15/x
3. Step 3: Cross multiply
   1,221.69x = 1,685.93 × 662.15
4. Step 4: Simplify right side
   1,221.69x = 1,116,343.18
5. Step 5: Solve for x
   x = 1,116,343.18/1,221.69
6. Step 6: Final answer
   x = 913.77