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Finding the Third Proportional to 15 and 18

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Solution

The third proportional to 15 and 18 is: 21.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    15 : 18 = 18 : x
  2. Step 2: Convert to fraction form
    15/18 = 18/x
  3. Step 3: Cross multiply
    15x = 18 × 18
  4. Step 4: Simplify right side
    15x = 324
  5. Step 5: Solve for x
    x = 324/15
  6. Step 6: Final answer
    x = 21.60

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Why These Related Problems?

These problems maintain the same ratio (1.20) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.