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Finding the Fourth Proportional to 15.65, 21.58 and 13.90

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Solution

The fourth proportional to 15.65, 21.58 and 13.90 is: 19.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.65 : 21.58 = 13.90 : x
  2. Step 2: Convert to fraction form
    15.65/21.58 = 13.90/x
  3. Step 3: Cross multiply
    15.65x = 21.58 × 13.90
  4. Step 4: Simplify right side
    15.65x = 299.85
  5. Step 5: Solve for x
    x = 299.85/15.65
  6. Step 6: Final answer
    x = 19.16

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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.