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Finding the Fourth Proportional to 387.40, 578.90 and 279.40

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Solution

The fourth proportional to 387.40, 578.90 and 279.40 is: 417.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.40 : 578.90 = 279.40 : x
  2. Step 2: Convert to fraction form
    387.40/578.90 = 279.40/x
  3. Step 3: Cross multiply
    387.40x = 578.90 × 279.40
  4. Step 4: Simplify right side
    387.40x = 161,744.66
  5. Step 5: Solve for x
    x = 161,744.66/387.40
  6. Step 6: Final answer
    x = 417.51

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.