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Finding the Fourth Proportional to 213.72, 320.58 and 90.42

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Solution

The fourth proportional to 213.72, 320.58 and 90.42 is: 135.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.72 : 320.58 = 90.42 : x
  2. Step 2: Convert to fraction form
    213.72/320.58 = 90.42/x
  3. Step 3: Cross multiply
    213.72x = 320.58 × 90.42
  4. Step 4: Simplify right side
    213.72x = 28,986.84
  5. Step 5: Solve for x
    x = 28,986.84/213.72
  6. Step 6: Final answer
    x = 135.63

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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.