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Finding the Fourth Proportional to 15.85, 21.81 and 15.70

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Solution

The fourth proportional to 15.85, 21.81 and 15.70 is: 21.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.85 : 21.81 = 15.70 : x
  2. Step 2: Convert to fraction form
    15.85/21.81 = 15.70/x
  3. Step 3: Cross multiply
    15.85x = 21.81 × 15.70
  4. Step 4: Simplify right side
    15.85x = 342.42
  5. Step 5: Solve for x
    x = 342.42/15.85
  6. Step 6: Final answer
    x = 21.60

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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.