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Finding the Fourth Proportional to 42, 57.91 and 28.20

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Solution

The fourth proportional to 42, 57.91 and 28.20 is: 38.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    42 : 57.91 = 28.20 : x
  2. Step 2: Convert to fraction form
    42/57.91 = 28.20/x
  3. Step 3: Cross multiply
    42x = 57.91 × 28.20
  4. Step 4: Simplify right side
    42x = 1,633.06
  5. Step 5: Solve for x
    x = 1,633.06/42
  6. Step 6: Final answer
    x = 38.88

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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.