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Finding the Fourth Proportional to 21.73, 30 and 20.87

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Solution

The fourth proportional to 21.73, 30 and 20.87 is: 28.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.73 : 30 = 20.87 : x
  2. Step 2: Convert to fraction form
    21.73/30 = 20.87/x
  3. Step 3: Cross multiply
    21.73x = 30 × 20.87
  4. Step 4: Simplify right side
    21.73x = 626.10
  5. Step 5: Solve for x
    x = 626.10/21.73
  6. Step 6: Final answer
    x = 28.81

Related Problems

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Double scale
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Similar ratio
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1.5x scale

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.