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Finding the Fourth Proportional to 289.40, 398.90 and 211.64

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Solution

The fourth proportional to 289.40, 398.90 and 211.64 is: 291.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    289.40 : 398.90 = 211.64 : x
  2. Step 2: Convert to fraction form
    289.40/398.90 = 211.64/x
  3. Step 3: Cross multiply
    289.40x = 398.90 × 211.64
  4. Step 4: Simplify right side
    289.40x = 84,423.20
  5. Step 5: Solve for x
    x = 84,423.20/289.40
  6. Step 6: Final answer
    x = 291.72

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.