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Finding the Fourth Proportional to 21, 31.46 and 18.77

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Solution

The fourth proportional to 21, 31.46 and 18.77 is: 28.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    21 : 31.46 = 18.77 : x
  2. Step 2: Convert to fraction form
    21/31.46 = 18.77/x
  3. Step 3: Cross multiply
    21x = 31.46 × 18.77
  4. Step 4: Simplify right side
    21x = 590.25
  5. Step 5: Solve for x
    x = 590.25/21
  6. Step 6: Final answer
    x = 28.11

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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.