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Finding the Fourth Proportional to 28.65, 39.57 and 21.42

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Solution

The fourth proportional to 28.65, 39.57 and 21.42 is: 29.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.65 : 39.57 = 21.42 : x
  2. Step 2: Convert to fraction form
    28.65/39.57 = 21.42/x
  3. Step 3: Cross multiply
    28.65x = 39.57 × 21.42
  4. Step 4: Simplify right side
    28.65x = 847.59
  5. Step 5: Solve for x
    x = 847.59/28.65
  6. Step 6: Final answer
    x = 29.58

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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.