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Finding the Fourth Proportional to 10.90, 15 and 8.70

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Solution

The fourth proportional to 10.90, 15 and 8.70 is: 11.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    10.90 : 15 = 8.70 : x
  2. Step 2: Convert to fraction form
    10.90/15 = 8.70/x
  3. Step 3: Cross multiply
    10.90x = 15 × 8.70
  4. Step 4: Simplify right side
    10.90x = 130.50
  5. Step 5: Solve for x
    x = 130.50/10.90
  6. Step 6: Final answer
    x = 11.97

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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.