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Finding the Fourth Proportional to 15.86, 21.88 and 9.72

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Solution

The fourth proportional to 15.86, 21.88 and 9.72 is: 13.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.86 : 21.88 = 9.72 : x
  2. Step 2: Convert to fraction form
    15.86/21.88 = 9.72/x
  3. Step 3: Cross multiply
    15.86x = 21.88 × 9.72
  4. Step 4: Simplify right side
    15.86x = 212.52
  5. Step 5: Solve for x
    x = 212.52/15.86
  6. Step 6: Final answer
    x = 13.40

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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.