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Finding the Fourth Proportional to 0.87, 1.20 and 0.57

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Solution

The fourth proportional to 0.87, 1.20 and 0.57 is: 0.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    0.87 : 1.20 = 0.57 : x
  2. Step 2: Convert to fraction form
    0.87/1.20 = 0.57/x
  3. Step 3: Cross multiply
    0.87x = 1.20 × 0.57
  4. Step 4: Simplify right side
    0.87x = 0.68
  5. Step 5: Solve for x
    x = 0.68/0.87
  6. Step 6: Final answer
    x = 0.78

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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.