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Finding the Fourth Proportional to 21.20, 32 and 20.80

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Solution

The fourth proportional to 21.20, 32 and 20.80 is: 31.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.20 : 32 = 20.80 : x
  2. Step 2: Convert to fraction form
    21.20/32 = 20.80/x
  3. Step 3: Cross multiply
    21.20x = 32 × 20.80
  4. Step 4: Simplify right side
    21.20x = 665.60
  5. Step 5: Solve for x
    x = 665.60/21.20
  6. Step 6: Final answer
    x = 31.40

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 (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.