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Finding the Fourth Proportional to 30.90, 42.58 and 30.76

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Solution

The fourth proportional to 30.90, 42.58 and 30.76 is: 42.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.90 : 42.58 = 30.76 : x
  2. Step 2: Convert to fraction form
    30.90/42.58 = 30.76/x
  3. Step 3: Cross multiply
    30.90x = 42.58 × 30.76
  4. Step 4: Simplify right side
    30.90x = 1,309.76
  5. Step 5: Solve for x
    x = 1,309.76/30.90
  6. Step 6: Final answer
    x = 42.39

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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.