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Finding the Fourth Proportional to 86.84, 119.70 and 79.40

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Solution

The fourth proportional to 86.84, 119.70 and 79.40 is: 109.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.84 : 119.70 = 79.40 : x
  2. Step 2: Convert to fraction form
    86.84/119.70 = 79.40/x
  3. Step 3: Cross multiply
    86.84x = 119.70 × 79.40
  4. Step 4: Simplify right side
    86.84x = 9,504.18
  5. Step 5: Solve for x
    x = 9,504.18/86.84
  6. Step 6: Final answer
    x = 109.44

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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.