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Finding the Fourth Proportional to 42.99, 64.45 and 21.27

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Solution

The fourth proportional to 42.99, 64.45 and 21.27 is: 31.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.99 : 64.45 = 21.27 : x
  2. Step 2: Convert to fraction form
    42.99/64.45 = 21.27/x
  3. Step 3: Cross multiply
    42.99x = 64.45 × 21.27
  4. Step 4: Simplify right side
    42.99x = 1,370.64
  5. Step 5: Solve for x
    x = 1,370.64/42.99
  6. Step 6: Final answer
    x = 31.89

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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.