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Finding the Fourth Proportional to 8.42, 11.59 and 7.21

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Solution

The fourth proportional to 8.42, 11.59 and 7.21 is: 9.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.42 : 11.59 = 7.21 : x
  2. Step 2: Convert to fraction form
    8.42/11.59 = 7.21/x
  3. Step 3: Cross multiply
    8.42x = 11.59 × 7.21
  4. Step 4: Simplify right side
    8.42x = 83.52
  5. Step 5: Solve for x
    x = 83.52/8.42
  6. Step 6: Final answer
    x = 9.92

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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.