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Finding the Fourth Proportional to 1,378.71, 1,902.60 and 789.21

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Solution

The fourth proportional to 1,378.71, 1,902.60 and 789.21 is: 1,089.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.71 : 1,902.60 = 789.21 : x
  2. Step 2: Convert to fraction form
    1,378.71/1,902.60 = 789.21/x
  3. Step 3: Cross multiply
    1,378.71x = 1,902.60 × 789.21
  4. Step 4: Simplify right side
    1,378.71x = 1,501,550.95
  5. Step 5: Solve for x
    x = 1,501,550.95/1,378.71
  6. Step 6: Final answer
    x = 1,089.10

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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.