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Finding the Fourth Proportional to 639.75, 959.85 and 315.35

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Solution

The fourth proportional to 639.75, 959.85 and 315.35 is: 473.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.75 : 959.85 = 315.35 : x
  2. Step 2: Convert to fraction form
    639.75/959.85 = 315.35/x
  3. Step 3: Cross multiply
    639.75x = 959.85 × 315.35
  4. Step 4: Simplify right side
    639.75x = 302,683.90
  5. Step 5: Solve for x
    x = 302,683.90/639.75
  6. Step 6: Final answer
    x = 473.13

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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.