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Finding the Fourth Proportional to 30.70, 42.32 and 28.90

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Solution

The fourth proportional to 30.70, 42.32 and 28.90 is: 39.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.70 : 42.32 = 28.90 : x
  2. Step 2: Convert to fraction form
    30.70/42.32 = 28.90/x
  3. Step 3: Cross multiply
    30.70x = 42.32 × 28.90
  4. Step 4: Simplify right side
    30.70x = 1,223.05
  5. Step 5: Solve for x
    x = 1,223.05/30.70
  6. Step 6: Final answer
    x = 39.84

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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.