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Finding the Fourth Proportional to 2.80, 4.20 and 1.29

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Solution

The fourth proportional to 2.80, 4.20 and 1.29 is: 1.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    2.80 : 4.20 = 1.29 : x
  2. Step 2: Convert to fraction form
    2.80/4.20 = 1.29/x
  3. Step 3: Cross multiply
    2.80x = 4.20 × 1.29
  4. Step 4: Simplify right side
    2.80x = 5.43
  5. Step 5: Solve for x
    x = 5.43/2.80
  6. Step 6: Final answer
    x = 1.94

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.