Finding the Fourth Proportional to 2,152.68, 2,970.72 and 1,221

Step by Step Solution

1. Step 1: Write the proportion equation
   2,152.68 : 2,970.72 = 1,221 : x
2. Step 2: Convert to fraction form
   2,152.68/2,970.72 = 1,221/x
3. Step 3: Cross multiply
   2,152.68x = 2,970.72 × 1,221
4. Step 4: Simplify right side
   2,152.68x = 3,627,249.12
5. Step 5: Solve for x
   x = 3,627,249.12/2,152.68
6. Step 6: Final answer
   x = 1,684.99