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Finding the Fourth Proportional to 21, 28.91 and 18.69

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Solution

The fourth proportional to 21, 28.91 and 18.69 is: 25.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    21 : 28.91 = 18.69 : x
  2. Step 2: Convert to fraction form
    21/28.91 = 18.69/x
  3. Step 3: Cross multiply
    21x = 28.91 × 18.69
  4. Step 4: Simplify right side
    21x = 540.37
  5. Step 5: Solve for x
    x = 540.37/21
  6. Step 6: Final answer
    x = 25.73

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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.