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Finding the Fourth Proportional to 1,220, 1,683.68 and 668

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Solution

The fourth proportional to 1,220, 1,683.68 and 668 is: 921.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,220 : 1,683.68 = 668 : x
  2. Step 2: Convert to fraction form
    1,220/1,683.68 = 668/x
  3. Step 3: Cross multiply
    1,220x = 1,683.68 × 668
  4. Step 4: Simplify right side
    1,220x = 1,124,698.24
  5. Step 5: Solve for x
    x = 1,124,698.24/1,220
  6. Step 6: Final answer
    x = 921.88

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.