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Finding the Fourth Proportional to 1,378.92, 1,902.96 and 789.40

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Solution

The fourth proportional to 1,378.92, 1,902.96 and 789.40 is: 1,089.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.92 : 1,902.96 = 789.40 : x
  2. Step 2: Convert to fraction form
    1,378.92/1,902.96 = 789.40/x
  3. Step 3: Cross multiply
    1,378.92x = 1,902.96 × 789.40
  4. Step 4: Simplify right side
    1,378.92x = 1,502,196.62
  5. Step 5: Solve for x
    x = 1,502,196.62/1,378.92
  6. Step 6: Final answer
    x = 1,089.40

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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.