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Finding the Fourth Proportional to 639.70, 959.55 and 206.86

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Solution

The fourth proportional to 639.70, 959.55 and 206.86 is: 310.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.70 : 959.55 = 206.86 : x
  2. Step 2: Convert to fraction form
    639.70/959.55 = 206.86/x
  3. Step 3: Cross multiply
    639.70x = 959.55 × 206.86
  4. Step 4: Simplify right side
    639.70x = 198,492.51
  5. Step 5: Solve for x
    x = 198,492.51/639.70
  6. Step 6: Final answer
    x = 310.29

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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.