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Finding the Fourth Proportional to 30.80, 42.47 and 30.39

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Solution

The fourth proportional to 30.80, 42.47 and 30.39 is: 41.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.80 : 42.47 = 30.39 : x
  2. Step 2: Convert to fraction form
    30.80/42.47 = 30.39/x
  3. Step 3: Cross multiply
    30.80x = 42.47 × 30.39
  4. Step 4: Simplify right side
    30.80x = 1,290.51
  5. Step 5: Solve for x
    x = 1,290.51/30.80
  6. Step 6: Final answer
    x = 41.91

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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.