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Finding the Fourth Proportional to 1,378.76, 1,902.79 and 789.48

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Solution

The fourth proportional to 1,378.76, 1,902.79 and 789.48 is: 1,089.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.76 : 1,902.79 = 789.48 : x
  2. Step 2: Convert to fraction form
    1,378.76/1,902.79 = 789.48/x
  3. Step 3: Cross multiply
    1,378.76x = 1,902.79 × 789.48
  4. Step 4: Simplify right side
    1,378.76x = 1,502,215.64
  5. Step 5: Solve for x
    x = 1,502,215.64/1,378.76
  6. Step 6: Final answer
    x = 1,089.55

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Half scale
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Double scale
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1.5x scale

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.