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Finding the Fourth Proportional to 6.61, 9.05 and 6.40

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Solution

The fourth proportional to 6.61, 9.05 and 6.40 is: 8.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    6.61 : 9.05 = 6.40 : x
  2. Step 2: Convert to fraction form
    6.61/9.05 = 6.40/x
  3. Step 3: Cross multiply
    6.61x = 9.05 × 6.40
  4. Step 4: Simplify right side
    6.61x = 57.91
  5. Step 5: Solve for x
    x = 57.91/6.61
  6. Step 6: Final answer
    x = 8.76

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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.