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Finding the Fourth Proportional to 639.92, 959.60 and 315.20

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Solution

The fourth proportional to 639.92, 959.60 and 315.20 is: 472.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.92 : 959.60 = 315.20 : x
  2. Step 2: Convert to fraction form
    639.92/959.60 = 315.20/x
  3. Step 3: Cross multiply
    639.92x = 959.60 × 315.20
  4. Step 4: Simplify right side
    639.92x = 302,465.92
  5. Step 5: Solve for x
    x = 302,465.92/639.92
  6. Step 6: Final answer
    x = 472.66

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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.