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Finding the Fourth Proportional to 15.87, 21.75 and 15.57

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Solution

The fourth proportional to 15.87, 21.75 and 15.57 is: 21.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.87 : 21.75 = 15.57 : x
  2. Step 2: Convert to fraction form
    15.87/21.75 = 15.57/x
  3. Step 3: Cross multiply
    15.87x = 21.75 × 15.57
  4. Step 4: Simplify right side
    15.87x = 338.65
  5. Step 5: Solve for x
    x = 338.65/15.87
  6. Step 6: Final answer
    x = 21.34

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.