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Finding the Fourth Proportional to 1,378.91, 1,902.90 and 789.45

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Solution

The fourth proportional to 1,378.91, 1,902.90 and 789.45 is: 1,089.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.91 : 1,902.90 = 789.45 : x
  2. Step 2: Convert to fraction form
    1,378.91/1,902.90 = 789.45/x
  3. Step 3: Cross multiply
    1,378.91x = 1,902.90 × 789.45
  4. Step 4: Simplify right side
    1,378.91x = 1,502,239.36
  5. Step 5: Solve for x
    x = 1,502,239.36/1,378.91
  6. Step 6: Final answer
    x = 1,089.44

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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.