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Finding the Fourth Proportional to 1.38, 1.91 and 0.78

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Solution

The fourth proportional to 1.38, 1.91 and 0.78 is: 1.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    1.38 : 1.91 = 0.78 : x
  2. Step 2: Convert to fraction form
    1.38/1.91 = 0.78/x
  3. Step 3: Cross multiply
    1.38x = 1.91 × 0.78
  4. Step 4: Simplify right side
    1.38x = 1.48
  5. Step 5: Solve for x
    x = 1.48/1.38
  6. Step 6: Final answer
    x = 1.07

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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.