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Finding the Fourth Proportional to 0.78, 1.08 and 0.42

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Solution

The fourth proportional to 0.78, 1.08 and 0.42 is: 0.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    0.78 : 1.08 = 0.42 : x
  2. Step 2: Convert to fraction form
    0.78/1.08 = 0.42/x
  3. Step 3: Cross multiply
    0.78x = 1.08 × 0.42
  4. Step 4: Simplify right side
    0.78x = 0.45
  5. Step 5: Solve for x
    x = 0.45/0.78
  6. Step 6: Final answer
    x = 0.58

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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.