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Finding the Fourth Proportional to 839.40, 1,258.47 and 319.35

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Solution

The fourth proportional to 839.40, 1,258.47 and 319.35 is: 478.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.40 : 1,258.47 = 319.35 : x
  2. Step 2: Convert to fraction form
    839.40/1,258.47 = 319.35/x
  3. Step 3: Cross multiply
    839.40x = 1,258.47 × 319.35
  4. Step 4: Simplify right side
    839.40x = 401,892.39
  5. Step 5: Solve for x
    x = 401,892.39/839.40
  6. Step 6: Final answer
    x = 478.79

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.