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Finding the Fourth Proportional to 98.97, 136.68 and 78.40

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Solution

The fourth proportional to 98.97, 136.68 and 78.40 is: 108.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    98.97 : 136.68 = 78.40 : x
  2. Step 2: Convert to fraction form
    98.97/136.68 = 78.40/x
  3. Step 3: Cross multiply
    98.97x = 136.68 × 78.40
  4. Step 4: Simplify right side
    98.97x = 10,715.26
  5. Step 5: Solve for x
    x = 10,715.26/98.97
  6. Step 6: Final answer
    x = 108.27

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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.