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Finding the Fourth Proportional to 28, 42 and 13.75

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Solution

The fourth proportional to 28, 42 and 13.75 is: 20.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    28 : 42 = 13.75 : x
  2. Step 2: Convert to fraction form
    28/42 = 13.75/x
  3. Step 3: Cross multiply
    28x = 42 × 13.75
  4. Step 4: Simplify right side
    28x = 577.50
  5. Step 5: Solve for x
    x = 577.50/28
  6. Step 6: Final answer
    x = 20.63

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