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Finding the Fourth Proportional to 15.72, 21.70 and 11.40

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Solution

The fourth proportional to 15.72, 21.70 and 11.40 is: 15.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.72 : 21.70 = 11.40 : x
  2. Step 2: Convert to fraction form
    15.72/21.70 = 11.40/x
  3. Step 3: Cross multiply
    15.72x = 21.70 × 11.40
  4. Step 4: Simplify right side
    15.72x = 247.38
  5. Step 5: Solve for x
    x = 247.38/15.72
  6. Step 6: Final answer
    x = 15.74

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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.