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Finding the Fourth Proportional to 100.21, 138.28 and 56.54

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Solution

The fourth proportional to 100.21, 138.28 and 56.54 is: 78.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.21 : 138.28 = 56.54 : x
  2. Step 2: Convert to fraction form
    100.21/138.28 = 56.54/x
  3. Step 3: Cross multiply
    100.21x = 138.28 × 56.54
  4. Step 4: Simplify right side
    100.21x = 7,817.38
  5. Step 5: Solve for x
    x = 7,817.38/100.21
  6. Step 6: Final answer
    x = 78.01

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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.