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Finding the Fourth Proportional to 101.74, 140.24 and 78.40

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Solution

The fourth proportional to 101.74, 140.24 and 78.40 is: 108.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    101.74 : 140.24 = 78.40 : x
  2. Step 2: Convert to fraction form
    101.74/140.24 = 78.40/x
  3. Step 3: Cross multiply
    101.74x = 140.24 × 78.40
  4. Step 4: Simplify right side
    101.74x = 10,994.82
  5. Step 5: Solve for x
    x = 10,994.82/101.74
  6. Step 6: Final answer
    x = 108.07

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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.