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Finding the Fourth Proportional to 39.21, 58.78 and 18.91

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Solution

The fourth proportional to 39.21, 58.78 and 18.91 is: 28.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.21 : 58.78 = 18.91 : x
  2. Step 2: Convert to fraction form
    39.21/58.78 = 18.91/x
  3. Step 3: Cross multiply
    39.21x = 58.78 × 18.91
  4. Step 4: Simplify right side
    39.21x = 1,111.53
  5. Step 5: Solve for x
    x = 1,111.53/39.21
  6. Step 6: Final answer
    x = 28.35

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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.