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Finding the Fourth Proportional to 42.81, 64.22 and 21.14

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Solution

The fourth proportional to 42.81, 64.22 and 21.14 is: 31.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.81 : 64.22 = 21.14 : x
  2. Step 2: Convert to fraction form
    42.81/64.22 = 21.14/x
  3. Step 3: Cross multiply
    42.81x = 64.22 × 21.14
  4. Step 4: Simplify right side
    42.81x = 1,357.18
  5. Step 5: Solve for x
    x = 1,357.18/42.81
  6. Step 6: Final answer
    x = 31.70

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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.