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Finding the Fourth Proportional to 30.78, 42.59 and 26.40

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Solution

The fourth proportional to 30.78, 42.59 and 26.40 is: 36.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.78 : 42.59 = 26.40 : x
  2. Step 2: Convert to fraction form
    30.78/42.59 = 26.40/x
  3. Step 3: Cross multiply
    30.78x = 42.59 × 26.40
  4. Step 4: Simplify right side
    30.78x = 1,124.38
  5. Step 5: Solve for x
    x = 1,124.38/30.78
  6. Step 6: Final answer
    x = 36.53

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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.