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Finding the Fourth Proportional to 30.55, 42.10 and 28.75

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Solution

The fourth proportional to 30.55, 42.10 and 28.75 is: 39.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.55 : 42.10 = 28.75 : x
  2. Step 2: Convert to fraction form
    30.55/42.10 = 28.75/x
  3. Step 3: Cross multiply
    30.55x = 42.10 × 28.75
  4. Step 4: Simplify right side
    30.55x = 1,210.38
  5. Step 5: Solve for x
    x = 1,210.38/30.55
  6. Step 6: Final answer
    x = 39.62

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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.