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Finding the Fourth Proportional to 79.42, 109.62 and 70.78

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Solution

The fourth proportional to 79.42, 109.62 and 70.78 is: 97.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.42 : 109.62 = 70.78 : x
  2. Step 2: Convert to fraction form
    79.42/109.62 = 70.78/x
  3. Step 3: Cross multiply
    79.42x = 109.62 × 70.78
  4. Step 4: Simplify right side
    79.42x = 7,758.90
  5. Step 5: Solve for x
    x = 7,758.90/79.42
  6. Step 6: Final answer
    x = 97.69

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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.