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Finding the Fourth Proportional to 15.70, 21.64 and 15.42

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Solution

The fourth proportional to 15.70, 21.64 and 15.42 is: 21.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.70 : 21.64 = 15.42 : x
  2. Step 2: Convert to fraction form
    15.70/21.64 = 15.42/x
  3. Step 3: Cross multiply
    15.70x = 21.64 × 15.42
  4. Step 4: Simplify right side
    15.70x = 333.69
  5. Step 5: Solve for x
    x = 333.69/15.70
  6. Step 6: Final answer
    x = 21.25

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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.