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Finding the Fourth Proportional to 1,680.80, 2,519.40 and 640.40

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Solution

The fourth proportional to 1,680.80, 2,519.40 and 640.40 is: 959.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,680.80 : 2,519.40 = 640.40 : x
  2. Step 2: Convert to fraction form
    1,680.80/2,519.40 = 640.40/x
  3. Step 3: Cross multiply
    1,680.80x = 2,519.40 × 640.40
  4. Step 4: Simplify right side
    1,680.80x = 1,613,423.76
  5. Step 5: Solve for x
    x = 1,613,423.76/1,680.80
  6. Step 6: Final answer
    x = 959.91

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.