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Finding the Fourth Proportional to 74.40, 102.80 and 57.12

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Solution

The fourth proportional to 74.40, 102.80 and 57.12 is: 78.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.40 : 102.80 = 57.12 : x
  2. Step 2: Convert to fraction form
    74.40/102.80 = 57.12/x
  3. Step 3: Cross multiply
    74.40x = 102.80 × 57.12
  4. Step 4: Simplify right side
    74.40x = 5,871.94
  5. Step 5: Solve for x
    x = 5,871.94/74.40
  6. Step 6: Final answer
    x = 78.92

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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.