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Finding the Fourth Proportional to 916.80, 1,375.20 and 430.40

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Solution

The fourth proportional to 916.80, 1,375.20 and 430.40 is: 645.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    916.80 : 1,375.20 = 430.40 : x
  2. Step 2: Convert to fraction form
    916.80/1,375.20 = 430.40/x
  3. Step 3: Cross multiply
    916.80x = 1,375.20 × 430.40
  4. Step 4: Simplify right side
    916.80x = 591,879.20
  5. Step 5: Solve for x
    x = 591,879.20/916.80
  6. Step 6: Final answer
    x = 645.59

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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.