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Finding the Fourth Proportional to 21.07, 31.58 and 13.47

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Solution

The fourth proportional to 21.07, 31.58 and 13.47 is: 20.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.07 : 31.58 = 13.47 : x
  2. Step 2: Convert to fraction form
    21.07/31.58 = 13.47/x
  3. Step 3: Cross multiply
    21.07x = 31.58 × 13.47
  4. Step 4: Simplify right side
    21.07x = 425.38
  5. Step 5: Solve for x
    x = 425.38/21.07
  6. Step 6: Final answer
    x = 20.19

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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.