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Finding the Fourth Proportional to 639.40, 957.90 and 330.20

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Solution

The fourth proportional to 639.40, 957.90 and 330.20 is: 494.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.40 : 957.90 = 330.20 : x
  2. Step 2: Convert to fraction form
    639.40/957.90 = 330.20/x
  3. Step 3: Cross multiply
    639.40x = 957.90 × 330.20
  4. Step 4: Simplify right side
    639.40x = 316,298.58
  5. Step 5: Solve for x
    x = 316,298.58/639.40
  6. Step 6: Final answer
    x = 494.68

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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.