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Finding the Fourth Proportional to 8.40, 11.57 and 7.84

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Solution

The fourth proportional to 8.40, 11.57 and 7.84 is: 10.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.40 : 11.57 = 7.84 : x
  2. Step 2: Convert to fraction form
    8.40/11.57 = 7.84/x
  3. Step 3: Cross multiply
    8.40x = 11.57 × 7.84
  4. Step 4: Simplify right side
    8.40x = 90.64
  5. Step 5: Solve for x
    x = 90.64/8.40
  6. Step 6: Final answer
    x = 10.79

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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.