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Finding the Fourth Proportional to 30.98, 42.75 and 28.42

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Solution

The fourth proportional to 30.98, 42.75 and 28.42 is: 39.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.98 : 42.75 = 28.42 : x
  2. Step 2: Convert to fraction form
    30.98/42.75 = 28.42/x
  3. Step 3: Cross multiply
    30.98x = 42.75 × 28.42
  4. Step 4: Simplify right side
    30.98x = 1,214.85
  5. Step 5: Solve for x
    x = 1,214.85/30.98
  6. Step 6: Final answer
    x = 39.21

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1.5x scale

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.