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Finding the Fourth Proportional to 1.78, 2.66 and 1.28

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Solution

The fourth proportional to 1.78, 2.66 and 1.28 is: 1.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1.78 : 2.66 = 1.28 : x
  2. Step 2: Convert to fraction form
    1.78/2.66 = 1.28/x
  3. Step 3: Cross multiply
    1.78x = 2.66 × 1.28
  4. Step 4: Simplify right side
    1.78x = 3.39
  5. Step 5: Solve for x
    x = 3.39/1.78
  6. Step 6: Final answer
    x = 1.90

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.