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Finding the Fourth Proportional to 28.40, 42.47 and 25.21

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Solution

The fourth proportional to 28.40, 42.47 and 25.21 is: 37.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.40 : 42.47 = 25.21 : x
  2. Step 2: Convert to fraction form
    28.40/42.47 = 25.21/x
  3. Step 3: Cross multiply
    28.40x = 42.47 × 25.21
  4. Step 4: Simplify right side
    28.40x = 1,070.83
  5. Step 5: Solve for x
    x = 1,070.83/28.40
  6. Step 6: Final answer
    x = 37.70

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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.