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Finding the Fourth Proportional to 74.42, 102.78 and 71.72

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Solution

The fourth proportional to 74.42, 102.78 and 71.72 is: 99.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.42 : 102.78 = 71.72 : x
  2. Step 2: Convert to fraction form
    74.42/102.78 = 71.72/x
  3. Step 3: Cross multiply
    74.42x = 102.78 × 71.72
  4. Step 4: Simplify right side
    74.42x = 7,371.38
  5. Step 5: Solve for x
    x = 7,371.38/74.42
  6. Step 6: Final answer
    x = 99.05

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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.